Atomic Structure
Unit 3
http://www.unit5.org/chemistry
Guiding Questions
How do we know atoms exist?
How do we know that electrons, protons, and
neutrons exist?
What is radiation and what does it come from?
Is radiation safe?
Where does matter come from?
How are elements formed?
Are all atoms of an element the same?
How do we measure atoms if they are so small?
How do we know what stars are made of?
What is wrong with this picture?
Table of Contents
‘Atomic Structure’
A). Development of the Atom
Dalton Model of the Atom
Thomson
Rutherford
Bohr
Quantum Mechanical
Review
Millikan Oil Drop
The Light slides have been moved to a separate PP.
C). Light
Frequency and Wavelength
Emission Spectra
Excited state vs. Ground State
Hydrogen Spectral Lines
Electromagnetic spectrum
Color
Photoelectric Effect
B). Particles in the Atom
Electron Configuration & Orbitals
Electron Configurations
Periodic Table – Orbital filling order
Isotopes
The Greeks
History of the Atom
• Not the history of atom, but
the idea of the atom
• In 400 B.C the Greeks tried to
understand matter
(chemicals) and broke them
down into earth, wind, fire,
and air.
~
~
• Democritus and Leucippus
Greek philosophers
Greek Model
“To understand the very large,
we must understand the very small.”
Democritus
• Greek philosopher
• Idea of ‘democracy’
• Idea of ‘atomos’
– Atomos = ‘indivisible’
– ‘Atom’ is derived
• No experiments to support
idea
• Continuous vs. discontinuous
theory of matter
Democritus’s model of atom
No protons, electrons, or neutrons
Solid and INDESTRUCTABLE
Democritus
DEMOCRITUS (400 BC) – First Atomic Hypothesis
Atomos: Greek for “uncuttable”. Chop up a piece of matter until you reach the atomos.
Properties of atoms:
• indestructible.
• changeable, however, into different forms.
• an infinite number of kinds so there are an infinite number of elements.
• hard substances have rough, prickly atoms that stick together.
• liquids have round, smooth atoms that slide over one another.
• smell is caused by atoms interacting with the nose – rough atoms hurt.
• sleep is caused by atoms escaping the brain.
• death – too many escaped or didn’t return.
• the heart is the center of anger.
• the brain is the center of thought.
• the liver is the seat of desire.
“Nothing exists but atoms and space, all else is opinion”.
Four Element Theory
FIRE
• Plato was an atomist
• Thought all matter was
composed of 4 elements:
–
–
–
–
–
Earth (cool, heavy)
Water (wet)
Fire (hot)
Air (light)
Ether (close to heaven)
Hot
Dry
‘MATTER’
AIR
Wet
EARTH
Cold
WATER
Relation of the four elements and the four qualities
Blend these “elements” in different proportions to get all substances
Some Early Ideas on Matter
Anaxagoras
(Greek, born 500 B.C.)
–Suggested every substance had its own kind of “seeds” that clustered together to
make the substance, much as our atoms cluster to make molecules.
Empedocles
(Greek, born in Sicily, 490 B.C.)
–Suggested there were only four basic seeds – earth, air, fire, and water. The
elementary substances (atoms to us) combined in various ways to make
everything.
Democritus
(Thracian, born 470 B.C.)
–Actually proposed the word atom (indivisible) because he believed that all
matter consisted of such tiny units with voids between, an idea quite similar to
our own beliefs. It was rejected by Aristotle and thus lost for 2000 years.
Aristotle
(Greek, born 384 B.C.)
–Added the idea of “qualities” – heat, cold, dryness, moisture – as basic elements
which combined as shown in the diagram (previous page).
Hot + dry made fire; hot + wet made air, and so on.
O’Connor Davis, MacNab, McClellan, CHEMISTRY Experiments and Principles 1982, page 26,
Early Ideas on Elements
Robert Boyle stated...
– A substance was an
element unless it could
be broken down to two
or more simpler
substances.
– Air therefore could not
be an element because
it could be broken down
in to many pure
substances.
Robert Boyle
Foundations of Atomic Theory
Law of Conservation of Mass
Mass is neither destroyed nor created during ordinary chemical
reactions.
Law of Definite Proportions
The fact that a chemical compound contains the same elements
in exactly the same proportions by mass regardless of the size
of the sample or source of the compound.
Law of Multiple Proportions
If two or more different compounds are composed of the
same two elements, then the ratio of the masses of the
second element combined with a certain mass of the first
elements is always a ratio of small whole numbers.
Conservation of Atoms
2 H2 + O2
2 H2O
John Dalton
H
H
H2
O
H
O2
+
H2
H
O
H2O
O
H 2O
H
H
O
H
H
4 atoms hydrogen
2 atoms oxygen
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 204
4 atoms hydrogen
2 atoms oxygen
Legos are Similar to Atoms
H
H2
H
H
O
+
H2
H
H
O2
H
O
H 2O
H
O
O
H
H 2O
Lego's can be taken apart and built into many different things.
Atoms can be rearranged into different substances.
Conservation of Mass
High
voltage
electrodes
Before reaction
After reaction
glass
chamber
O2
High
voltage
H2O
O2
5.0 g H2
H2
80
0 g H2
g O2
300 g (mass
of chamber)
+
385 g total
45
? g H2O
40 g O2
300 g (mass
of chamber)
+
385 g total
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 204
Law of Definite Proportions
Joseph Louis Proust (1754 – 1826)
• Each compound has a specific ratio of
elements
• It is a ratio by mass
• Water is always 8 grams of oxygen for
every one gram of hydrogen
The Law of Multiple Proportions
• Dalton could not use his theory to determine the
elemental compositions of chemical compounds
because he had no reliable scale of atomic masses.
• Dalton’s data led to a general statement known as the
law of multiple proportions.
• Law states that when two elements form a series of
compounds, the ratios of the masses of the second
element that are present per gram of the first element
can almost always be expressed as the ratios of
integers.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Daltons Atomic Theory
• Dalton stated that
elements consisted of
tiny particles called atoms
• He also called the
elements pure
substances because all
atoms of an element
were identical and that in
particular they had the
same mass.
Dalton’s Atomic Theory
1. All matter consists of tiny particles.
Dalton, like the Greeks, called these particles “atoms”.
2. Atoms of one element can neither be subdivided nor changed into
atoms of any other element.
3. Atoms can neither be created nor destroyed.
4. All atoms of the same element are identical in mass, size, and
other properties.
5. Atoms of one element differ in mass and other properties from
atoms of other elements.
6. In compounds, atoms of different elements combine in simple, whole
number ratios.
Dalton’s Symbols
John Dalton
1808
Daltons’ Models of Atoms
Carbon dioxide, CO2
Water, H2O
Methane, CH4
History: On The Human Side
1834
1895
1896
1896
1897
1898
1899
1900
Michael Faraday - electrolysis experiments
suggested electrical nature of matter
Wilhelm Roentgen - discovered X-rays when
cathode rays strike anode
Henri Becquerel - discovered "uranic rays" and
radioactivity
Marie (Marya Sklodowska) and Pierre Curie discovered that radiation is a property of the
atom, and not due to chemical reaction.
(Marie named this property radioactivity.)
Joseph J. Thomson - discovered the electron
through Crookes tube experiments
Marie and Piere Curie - discovered the
radioactive elements polonium and radium
Ernest Rutherford - discovered alpha and beta
particles
Paul Villard - discovered gamma rays
1919
1932
1934
1938
1940
1941
1942
1903
1910
1911
Ernest Rutherford and Frederick Soddy established laws of radioactive decay and
transformation
Frederick Soddy - proposed the isotope concept
to explain the existence of more than one atomic
weight of radioelements
Ernest Rutherford - used alpha particles to
explore gold foil; discovered the nucleus and the
proton; proposed the nuclear theory of the atom
1944
1964
Ernest Rutherford - announced the first artificial
transmutation of atoms
James Chadwick - discovered the neutron by
alpha particle bombardment of Beryllium
Frederick Joliet and Irene Joliet Curie - produced
the first artificial radioisotope
Otto Hahn, Fritz Strassmann, Lise Meitner, and
Otto Frisch - discovered nuclear fission of
uranium-235 by neutron bombardment
Edwin M McMillan and Philip Abelson discovered the first transuranium element,
neptunium, by neutron irradiation of uranium in a
cyclotron
Glenn T. Seaborg, Edwin M. McMillan, Joseph
W. Kennedy and Arthur C. Wahl - announced
discovery of plutonium from beta particle
emission of neptunium
Enrico Fermi - produced the first nuclear fission
chain-reaction
Glenn T. Seaborg - proposed a new format for
the periodic table to show that a new actinide series of 14
elements would fall below and be analogous to the 14
lanthanide-series elements.
Murray Gell-Mann hypothesized that quarks are the
fundamental particles that make up all known subatomic
particles except leptons.
Radioactivity (1896)
1. rays or particles produced by
unstable nuclei
a. Alpha Rays – helium nucleus
b. Beta Part. – high speed electron
c. Gamma ray – high energy x-ray
2. Discovered by Becquerel –
exposed photographic film
3. Further work by Curies
Antoine-Henri Becquerel
(1852 - 1908)
Radioactivity
• One of the pieces of evidence for the
fact that atoms are made of smaller
particles came from the work of
Marie Curie (1876 - 1934).
• She discovered radioactivity, the
spontaneous disintegration of some
elements into smaller pieces.
Crookes Tube
William Crookes
Crookes tube
(Cathode ray tube)
Glow
Cathode
(-)
Anode
(+)
Mask holder
The Effect of an Obstruction on
Cathode Rays
High
voltage
source of
high voltage
shadow
cathode
yellow-green
fluorescence
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 117
Crooke’s Tube
-
voltage
source
William Crookes
+
vacuum tube
metal disks
magnet
Television Picture Tube
Blue beam
Green beam
Red beam
Glass window
Shadow mask
Fluorescent screen
Electron
gun
Electron
beam
Deflecting
electromagnets
Red beam
Green beam
Blue beam
Shadow mask
Fluorescent
screen with
phosphor dots
A Cathode Ray Tube
Source of
Electrical
Potential
Stream of negative
particles (electrons)
Metal Plate
Gas-filled
glass tube
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 58
Metal plate
Background Information
•
•
•
•
Cathode Rays
Form when high voltage is applied across
electrodes in a partially evacuated tube.
Originate at the cathode (negative electrode)
and move to the anode (positive electrode)
Carry energy and can do work
Travel in straight lines in the absence of an
external field
Cathode Ray Experiment
1897 Experimentation
• Using a cathode ray tube, Thomson was
able to deflect cathode rays with an
electrical field.
• The rays bent towards the positive pole,
indicating that they are negatively
charged.
The Effect of an Electric Field on
Cathode Rays
source of
high voltage
High
voltage
cathode
negative
plate
_
+
anode
positive
plate
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 117
Conclusions
• He compared the value with the mass/ charge ratio for the
lightest charged particle.
• By comparison, Thomson estimated that the cathode ray particle
weighed 1/1000 as much as hydrogen, the lightest atom.
• He concluded that atoms do contain subatomic particles - atoms
are divisible into smaller particles.
• This conclusion contradicted Dalton’s postulate and was not
widely accepted by fellow physicists and chemists of his day.
• Since any electrode material produces an identical ray, cathode
ray particles are present in all types of matter - a universal
negatively charged subatomic particle later named the electron
Conclusiones
• He comparado con el valor de la masa / carga más ligera para
la proporción de partículas cargadas.
• En comparación, Thomson calcula que las partículas de rayos
catódicos pesaba 1 / 1000 tanto como el hidrógeno, el átomo
más ligero.
• Él llegó a la conclusión de que los átomos contienen partículas
subatómicas, átomos de dividirse en partículas más pequeñas.
• Esta conclusión es contradicha Dalton postulado y no fue
ampliamente aceptada por sus compañeros físicos y químicos
de su época.
• Dado que todo el material del electrodo produce una idéntica de
rayos, rayos catódicos partículas están presentes en todos los
tipos de materia, universal negativamente cargado de partículas
subatómicas más tarde el nombre de electrón
(A) The effect of an obstruction on cathode rays
Cathode
Rays
High
voltage
shadow
source of
high voltage
cathode
yellow-green
fluorescence
•Cathode ray = electron
•Electrons have a
negative charge
(B) The effect of an electric field on cathode rays
negative
plate
High
voltage
source of
high voltage
source of
low voltage
cathode
+
anode
positive
plate
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, pages 117-118
J.J. Thomson
• He proved that atoms of
any element can be
made to emit tiny
negative particles.
• From this he concluded
that ALL atoms must
contain these negative
particles.
• He knew that atoms did
not have a net negative
charge and so there must
be balancing the negative
charge.
J.J. Thomson
William Thomson
(Lord Kelvin)
• In 1910 proposed
the Plum Pudding
model
– Negative electrons
were embedded into
a positively charged
spherical cloud.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 56
Spherical cloud of
Positive charge
Electrons
Thomson Model of the Atom
• J.J. Thomson discovered the electron and knew that
electrons could be emitted from matter (1897).
• William Thomson proposed that atoms consist of small,
negative electrons embedded in a massive, positive
sphere.
• The electrons were like currants in a plum pudding.
• This is called the ‘plum pudding’ model of the atom.
-
-
electrons
-
-
-
Rutherford
Ernest Rutherford (1871-1937)
PAPER
• Learned physics in
J.J. Thomson’ lab.
• Noticed that ‘alpha’
particles were
sometime deflected
by something in the
air.
• Gold-foil experiment
Animation by Raymond Chang – All rights reserved.
Rutherford ‘Scattering’
• In 1909 Rutherford undertook a series of experiments
• He fired a (alpha) particles at a very thin sample of gold foil
• According to the Thomson model the a particles would only
be slightly deflected
• Rutherford discovered that they were deflected through large
angles and could even be reflected straight back to the source
Lead collimator
Gold foil
a particle
source
q
Rutherford’s Apparatus
Rutherford received the 1908 Nobel Prize in Chemistry for his pioneering work in nuclear chemistry.
beam of alpha particles
radioactive
substance
circular ZnS - coated
fluorescent screen
gold foil
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 120
Rutherford’s Apparatus
beam of alpha particles
radioactive
substance
fluorescent screen
circular - ZnS coated
gold foil
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 120
Geiger-Muller Counter
Hans Geiger
Speaker gives
“click” for
each particle
Window
Particle
path
Argon atoms
Geiger Counter
Ionization of fill gas
takes place along
track of radiation
(-)
(+)
Speaker gives
“click” for
each particle
Metal tube
(negatively
charged)
Window
+
e-
e+
+
+ ee-
Ionizing
radiation
path
Atoms or molecules
of fill gas
Wilbraham, Staley, Matta, Waterman, Chemistry, 2002, page 857
Central wire electrode
(positively charged)
Free e- are attracted to
(+) electrode, completing
the circuit and generating
a current. The Geiger
counter then translates
the current reading into a
measure of radioactivity.
What he expected…
What he got…
richocheting
alpha particles
The Predicted Result:
expected
path
expected
marks on screen
Observed Result:
mark on
screen
likely alpha
particle path
Interpreting the
Observed Deflections
.
.
.
.
.
.
beam of
alpha
particles
.
.
.
.
.
undeflected
particles
.
.
.
.
.
gold foil
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 120
.
deflected particle
Rutherford Scattering (cont.)
Rutherford interpreted this result by suggesting that
the a particles interacted with very small and heavy
particles
Particle bounces off
of atom?
Case A
Case B
Particle goes through
atom?
Particle attracts
to atom?
Case C
Case D
.
Particle path is altered
as it passes through atom?
Table: hypothetical description of alpha particles
(based on properties of alpha radiation)
observation
hypothesis
alpha rays don’t diffract
... alpha radiation is a stream of particles
alpha rays deflect towards a negatively
charged plate and away from a positively
charged plate
... alpha particles have a positive charge
alpha rays are deflected only slightly by
an electric field; a cathode ray passing
through the same field is deflected
strongly
... alpha particles either have much
lower charge or much greater mass
than electrons
Copyright © 1997-2005 by Fred Senese
Explanation of Alpha-Scattering Results
Alpha particles
Nucleus
+
+
-
-
+
+
-
+
+
-
+
-
+
-
-
Plum-pudding atom
Nuclear atom
Thomson’s model
Rutherford’s model
Results of foil experiment if plumpudding had been correct.
Electrons scattered
throughout
-
+
-
positive
charges
+
+
+
+
-
-
+
+
+
-
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 57
-
Interpreting the Observed
Deflections
deflected particle
.
.
.
.
.
.
beam of
alpha
particles
.
.
.
.
.
.
.
.
.
.
gold foil
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 120
.
undeflected
particles
Rutherford’s
Gold-Leaf
Experiment
Conclusions:
Atom is mostly empty space
Nucleus has (+) charge
Electrons float around nucleus
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 120
• Hit moth driving car – no change in car
direction
• Hit deer – car changes direction
Alpha particle
moth
Gold Atom
deer
Large angle of deflection, must have hit massive object!
Oil Drop Experiment
oil droplets
+
Small hole
Charged plate
. . ... ................................... .
........................................
...... . ........ ........... ......................
..... ..... . . ........ ..... ............................................. .. oil atomizer
............... . ................................................ .
. . . . . . ...... .. . .... .
.. . . . .. . . . .
.. ..........
..
.
.
.
.
......
.
.......... .. .
................... ... .
.. ...................... .
..................... .. .
...... ..........................................
............................... ... .. . .
.. ....... ..... ..... .. .....
....... ... . . ...... ... .
.
.
. .... .. . ..
..... ... ..
.......... .. .. . .
.. .
..
.. . .... .
Charged plate
Robert Millikan
Telescope
oil droplet
under observation
Bohr’s Model
Nucleus
Electron
Orbit
Energy Levels
Bohr Model of Atom
Increasing energy
of orbits
n=3
e-
n=2
e-
n=1
ee-
e-
e-
ee-
e-
e-
eA photon is emitted
with energy E = hf
The Bohr model of the atom, like many ideas in
the history of science, was at first prompted by
and later partially disproved by experimentation.
http://en.wikipedia.org/wiki/Category:Chemistry
Modelo de Bohr del átomo
e-
n=2
ee-
n=1
ee-
n=3
El aumento de la energía
De las órbitas
e-
ee-
e-
e-
eUn fotón es emitido
Con la energía E = hf
El modelo de Bohr del átomo, al igual que en
muchas de las ideas la historia de la ciencia, en la
primera fue motivada por y más tarde parcialmente
desmentida por la experimentación.
http://en.wikipedia.org/wiki/Category:Chemistry
An unsatisfactory model
for the hydrogen atom
According to classical physics, light
should be emitted as the electron
circles the nucleus. A loss of energy
would cause the electron to be drawn
closer to the nucleus and eventually
spiral into it.
Hill, Petrucci, General Chemistry An Integrated Approach 2nd Edition, page 294
Quantum Mechanical Model
Niels Bohr &
Albert Einstein
Modern atomic theory describes the
electronic structure of the atom as the
probability of finding electrons within certain
regions of space (orbitals).
Modern View
• The atom is mostly empty space
• Two regions
– Nucleus
• protons and neutrons
– Electron cloud
• region where you might find an electron
The Experiment
• To test this he designed and experiment directing ‘alpha’
particles toward a thin metal foil.
– The foil was coated with a substance that produced flashes
when it was hit by an alpha particle.
Some a particles
are scattered
Source of
a particles
Beam of
a particles
Screen to detect
scattered a particles
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 56
Most particles
pass straight
through foil
Thin metal foil
Appling the Results to the Models
Alpha particles
Nucleus
+
+
-
-
+
+
-
+
+
-
+
-
+
-
-
Plum-pudding atom
Nuclear atom
Models of the Atom
"In science, a wrong theory can be valuable and better than no theory at all."
- Sir William L. Bragg
e
e
+
e
+
e
+
+
e
+e
+
e
e
+ e + e
Dalton’s
Greek model
model
(400
(1803)
B.C.)
Thomson’s plum-pudding
model (1897)
Bohr’s model
(1913)
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 125
-
- +
Rutherford’s model
(1909)
Charge-cloud model
(present)
Models of the Atom
e
e
+
e
-
+
e
+
+
e
+e
+e
e
+ e + e
Dalton’s
model
Greek model
(1803)
(400 B.C.)
1803 John Dalton
pictures atoms as
tiny, indestructible
particles, with no
internal structure.
1800
-
Thomson’s plum-pudding
model (1897)
- +
Rutherford’s model
(1909)
1897 J.J. Thomson, a British
1911 New Zealander
scientist, discovers the electron,
leading to his "plum-pudding"
model. He pictures electrons
embedded in a sphere of
positive electric charge.
Ernest Rutherford states
that an atom has a dense,
positively charged nucleus.
Electrons move randomly in
the space around the nucleus.
1805 ..................... 1895
1900
1905
1910
1904 Hantaro Nagaoka, a
Japanese physicist, suggests
that an atom has a central
nucleus. Electrons move in
orbits like the rings around Saturn.
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 125
1915
Bohr’s model
(1913)
1926 Erwin Schrödinger
1913 In Niels Bohr's
model, the electrons move
in spherical orbits at fixed
distances from the nucleus.
1920
1925
Charge-cloud model
(present)
1930
develops mathematical
equations to describe the
motion of electrons in
atoms. His work leads to
the electron cloud model.
1935
1940
1945
1924 Frenchman Louis
1932 James
de Broglie proposes that
moving particles like electrons
have some properties of waves.
Within a few years evidence is
collected to support his idea.
Chadwick, a British
physicist, confirms the
existence of neutrons,
which have no charge.
Atomic nuclei contain
neutrons and positively
charged protons.
Bohr Model
Neils Bohr
Planetary
model
After Rutherford’s discovery, Bohr
proposed that electrons travel in definite
orbits around the nucleus.
• Bohr’s contributions to the understanding of
atomic structure:
1. Electrons can occupy only certain regions of space,
called orbits.
2. Orbits closer to the nucleus are more stable —
they are at lower energy levels.
3. Electrons can move from one orbit to another by
absorbing or emitting energy, giving rise to
characteristic spectra.
• Bohr’s model could not explain
the spectra of atoms heavier
than hydrogen.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Particles in the Atom
Electrons
(-) charge
no mass
located outside the nucleus
1 amu
located inside the nucleus
1 amu
located inside the nucleus
Protons
(+) charge
Neutrons
no charge
Discovery of the Neutron
9
4
Be
+
4
2
He
12
6
C
+
1
0
n
James Chadwick bombarded beryllium-9 with alpha particles,
carbon-12 atoms were formed, and neutrons were emitted.
Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 764
*Walter Boethe
Subatomic particles
Name
Symbol
Relative
Charge mass
Actual
mass (g)
Electron
e-
-1
1/1840
9.11 x 10-28
Proton
p+
+1
1
1.67 x 10-24
Neutron
no
0
1
1.67 x 10-24
Subatomic Particles
ATOM
ATOM
NUCLEUS
NUCLEUS
ELECTRONS
ELECTRONS
PROTONS
PROTONS
NEUTRONS
NEUTRONS
POSITIVE
Positive
CHARGE
Charge
NEUTRAL
Neutral
CHARGE
Charge
NEGATIVE
CHARGE
Negative Charge
equal in a
Atomic
Most Number
of the atom’s mass.
neutral atom
equals the # of...
QUARKS
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Symbols
Contain the symbol of the element, the mass
number and the atomic number
# protons
+ # neutrons
mass number
# protons
Mass
number
Atomic
number
X
Symbols
• Find the
– number of protons = 9 +
– number of neutrons = 10
– number of electrons = 9
– Atomic number = 9
– Mass number = 19
19
9
F
Symbols
Find the
– number of protons = 35
– number of neutrons = 45
– number of electrons = 35
– Atomic number = 35
– Mass number = 80
http://www.chem.purdue.edu/gchelp/liquids/bromine.gif
80
35
Br
Symbols
Find the
– number of protons = 11
– number of neutrons = 12
– number of electrons = 11
– Atomic number = 11
– Mass number = 23
23
11
Na
Sodium atom
Symbols
Find the
– number of protons = 11
– number of neutrons = 12
– number of electrons = 10
– Atomic number = 11
– Mass number = 23
23
11
1+
Na
Sodium ion
Symbols
If an element has an atomic number of
23 and a mass number of 51 what is
the
– number of protons = 23
– number of neutrons = 28
– number of electrons = 23
– Complete symbol
51
23
V
Symbols
If an element has 60 protons and 84
neutrons what is the
– Atomic number = 60
= 144
– Mass number
– number of electrons = 60
– Complete symbol
144
60
Nd
Symbols
If a neutral atom of an element has 78
electrons and 117 neutrons what is the
– Atomic number = 78
– Mass number = 195
– number of protons = 78
– Complete symbol
195
78
Pt
Masses of Atoms

Mass Number

Isotopes

Ions

Relative Atomic Mass

Average Atomic Mass
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Atomic
Mass
p+
n0
e–
Ca
20
40
20
20
20
Ar
18
40
18
22
18
Br
35
80
35
45
35
20
18
35
Ca
Ar
Br
40.08
39.948
79.904
Bohr - Rutherford diagrams
• Putting all this together, we get B-R diagrams
• To draw them you must know the # of protons, neutrons,
and electrons (2,8,8,2 filling order)
• Draw protons (p+), (n0) in circle (i.e. “nucleus”)
• Draw electrons around in shells
He
2 p+
2 n0
Li
Li shorthand
3 p+
4 n0
3 p+
4 n0
2e– 1e–
Draw Be, B, Al and shorthand diagrams for O, Na
Be
B
Al
4 p+
5 n°
O
5 p+
6 n°
13 p+
14 n°
Na
8 p+ 2e– 6e–
8 n°
11 p+ 2e– 8e– 1e–
12 n°
Mass Number
• mass # = protons + neutrons
• always a whole number
Neutron
+
• NOT on the
Periodic Table!
Electrons
Nucleus
e-
+
e-
e-
+
+
+
+
Nucleus
e-
ee-
Carbon-12
Neutrons 6
Protons
6
Electrons 6
Proton
Isotopes
• Atoms of the same element with different
mass numbers.
• Nuclear symbol:
Mass #
12
Atomic #
6
• Hyphen notation: carbon-12
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
C
Isotopes
Neutron
+
Electrons
Nucleus
+
+
+
+
+
Nucleus
Proton
Proton
Nucleus
Carbon-12
Neutrons 6
Protons
6
Electrons 6
+
+
+
+
Neutron
Electrons
+
+
Carbon-14
Neutrons 8
Protons
6
Electrons 6
Nucleus
6Li
7Li
3 p+
3 n0
3 p+
4 n0
2e– 1e–
2e– 1e–
Neutron
Neutron
Electrons
Electrons
+
Nucleus
+
+
Nucleus
+
Nucleus
Lithium-6
Neutrons 3
Protons
3
Electrons 3
Proton
+
+
Nucleus
Lithium-7
Neutrons 4
Protons
3
Electrons 3
Proton
17
Cl
Isotopes
37
• Chlorine-37
– atomic #:
17
– mass #:
37
– # of protons:
17
– # of electrons: 17
– # of neutrons: 20
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
37
17
Cl
Relative Atomic Mass
•
12C
atom = 1.992 × 10-23 g
• atomic mass unit (amu)
• 1 amu = 1/12 the mass of a 12C atom
• 1 p = 1.007276 amu
1 n = 1.008665 amu
1 e- = 0.0005486 amu
+
Electrons
Nucleus
+
Neutron
+
+
+
+
Nucleus
Carbon-12
Neutrons 6
Protons
6
Electrons 6
Proton
Average Atomic Mass
• weighted average of all isotopes
• on the Periodic Table
• round to 2 decimal places
Avg.
(mass)(%) + (mass)(%)
Atomic =
100
Mass
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Average Atomic Mass
• EX: Calculate the avg. atomic mass of oxygen if its
abundance in nature is 99.76% 16O, 0.04% 17O, and
0.20% 18O.
Avg.
(16)(99.76) + (17)(0.04) + (18)(0.20)
16.00
Atomic =
=
amu
100
Mass
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Average Atomic Mass
• EX: Find chlorine’s average atomic mass
if approximately 8 of every 10 atoms are
chlorine-35 and 2 are chlorine-37.
Avg.
(35)(8) + (37)(2)
Atomic =
= 35.40 amu
10
Mass
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
17
100
Mass spectrum of chlorine. Elemental chlorine (Cl2) contains
only two isotopes: 34.97 amu (75.53%) and 36.97 (24.47%)
90
80
Cl-35
70
Abundance
AAM = (34.97 amu)(0.7553) + (36.97 amu)(0.2447)
60
AAM =
(26.412841 amu)
AAM =
+
(9.046559 amu)
35.4594 amu
50
40
30
Cl-37
20
10
0
34
36
35
Mass
37
Cl
35.4594
Mass Spectrophotometer
magnetic field
heaviest
ions
stream
of ions of
different
masses
electron
beam
gas
Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 138
lightest
ions
Weighing atoms
gas sample
enters here
.
ions accelerate
towards charged
slit
magnetic field
deflects lightest ions
most
filament current
ionizes the gas
The first mass spectrograph was
built in 1919 by F. W. Aston, who
received the 1922 Nobel Prize for
this accomplishment
ions separated by mass
expose film
• mass spectrometry is used to experimentally determine isotopic masses
and abundances
• interpreting mass spectra
• average atomic weights
- computed from isotopic masses and abundances
- significant figures of tabulated atomic weights gives some idea
of natural variation in isotopic abundances
Copyright © 1997-2005 by Fred Senese
Mass Spectrometry
198
200
202
Photographic plate
196
-
+
Stream of positive ions
Hill, Petrucci, General Chemistry An Integrated Approach 1999, page 320
199
201
204
Mass spectrum of mercury vapor
Mass Spectrum for Mercury
(The photographic record has been converted to a scale of relative number of atoms)
The percent natural abundances
for mercury isotopes are:
Hg-196
Hg-198
Hg-199
Hg-200
Hg-201
Hg-202
Hg-204
Relative number of atoms
30
25
198
0.146%
10.02%
16.84%
23.13%
13.22%
29.80%
6.85%
196
200
199
15
10
5
197
198
201
204
Mass spectrum of mercury vapor
20
196
202
199
200
Mass number
201
202
203
204
80
Hg
200.59
The percent natural abundances
for mercury isotopes are:
A
B
C
D
E
F
G
Hg-196
Hg-198
Hg-199
Hg-200
Hg-201
Hg-202
Hg-204
0.146%
10.02%
16.84%
23.13%
13.22%
29.80%
6.85%
(% "A")(mass "A") + (% "B")(mass "B") + (% "C")(mass "C") + (% "D")(mass "D") + (% "E")(mass "E") + (% F)(mass F) + (% G)(mass G) = AAM
(0.00146)(196) + (0.1002)(198) + (0.1684)(199) + (0.2313)(200) + (0.1322)(201) + (0.2980)(202) + (0.0685)(204) = x
0.28616 + 19.8396 + 33.5116 + 46.2600 + 26.5722 + 60.1960 + 13.974 = x
x = 200.63956 amu
92
Separation of Isotopes
U
238
Natural uranium, atomic weight = 238.029 g/mol
Density is 19 g/cm3. Melting point 1000oC.
Two main isotopes:
238
92
235
92
U
U
99.3%
0.7%
(238 amu) x (0.993) + (235 amu) x (0.007)
236.334 amu + 1.645 amu
Because isotopes are chemically identical
(same electronic structure), they cannot be
separated by chemistry.
So Physics separates them by diffusion or
centrifuge (mass spectrograph is too slow)…
237.979 amu
17
Cl
35.453
• Assume you have only two atoms of chlorine.
• One atom has a mass of 35 amu (Cl-35)
• The other atom has a mass of 36 amu (Cl-36)
• What is the average mass of these two isotopes?
35.5 amu
• Looking at the average atomic mass printed on the
periodic table...approximately what percentage is Cl-35
and Cl-36?
55% Cl-35 and 45% Cl-36 is a good approximation
17
Cl
35.453
Using our estimated % abundance data
55% Cl-35 and 45% Cl-36
calculate an average atomic mass for chlorine.
Average Atomic Mass = (% abundance of isotope "A")(mass "A") + (% "B")(mass "B")
AAM = (% abundance of isotope Cl-35)(mass Cl-35) + (% abundance of Cl-36)(mass Cl-36)
AAM = (0.55)(35 amu) + (0.45)(36 amu)
AAM = (19.25 amu) + (16.2 amu)
AAM = 35.45 amu
Isotopes
Dalton was wrong.
Atoms of the same element can have
different numbers of neutrons
different mass numbers
called isotopes
C-12
California WEB
vs.
C-14
Naming Isotopes
• Put the mass number after the name of
the element
• carbon- 12
• carbon -14
• uranium-235
California WEB
Using a periodic table and what you know about atomic
number, mass, isotopes, and electrons, fill in the chart:
Element
Symbol
Atomic
Number
Atomic
Mass
# of
protons
# of
neutron
# of
electron
8
8
8
39
Potassium
+1
Br
45
30
35
-1
30
Atomic Number = Number of Protons
Number of Protons + Number of Neutrons = Atomic Mass
Atom (no charge) : Protons = Electrons
Ion (cation) : Protons > Electrons
charge
Ion (anion) : Electrons > Protons
Using a periodic table and what you know about atomic
number, mass, isotopes, and electrons, fill in the chart:
ANSWER KEY
Element
Symbol
Atomic
Number
Atomic
Mass
# of
protons
# of
neutron
# of
electron
charge
Oxygen
O
8
16
8
8
8
0
Potassium
K
19
39
19
20
18
+1
Bromine
Br
35
80
35
45
36
-1
Zinc
Zn
30
35
30
65
30
0
Atomic Number = Number of Protons
Number of Protons + Number of Neutrons = Atomic Mass
Atom (no charge) : Protons = Electrons
Ion (cation) : Protons > Electrons
Ion (anion) : Electrons > Protons
Atomic Mass
•
•
•
•
•
How heavy is an atom of oxygen?
There are different kinds of oxygen atoms.
More concerned with average atomic mass.
Based on abundance of each element in nature.
Don’t use grams because the numbers would be
too small
Measuring Atomic Mass
• Unit is the Atomic Mass Unit (amu)
• One twelfth the mass of a carbon-12 atom.
• Each isotope has its own atomic mass we need
the average from percent abundance.
(1 amu)
(1 amu)
(1 amu)
(1 amu)
carbon atom
(1 amu)
(1 amu)
(1 amu)
(1 amu)
(12 amu)
(1 amu)
(1 amu)
(1 amu)
(1 amu)
Mass spectrums reflect the abundance of
naturally occurring isotopes.
Natural Abundance of Common Elements
Hydrogen
1H
= 99.985%
2H
= 0.015%
Carbon
12C
= 98.90%
13C
= 1.10%
Nitrogen
14N
= 99.63%
15N
= 0.37%
Oxygen
16O
= 99.762%
17O
= 0.038%
Sulfur
32S
= 95.02%
33S
= 0.75%
34S
= 4.21%
36S
= 0.02%
Chlorine
35Cl
= 75.77%
37Cl
= 24.23%
Bromine
79Br
= 50.69%
81Br
= 49.31%
18O
= 0.200%
For example….Methane
For carbon 1 in approximately 90
atoms are carbon-13
The rest are carbon-12 the isotope that
is 98.9% abundant.
So, for approximately 90 methane
molecules…1 carbon is carbon-13
C-13
Where’s
Waldo?
Where’s
Waldo?
Calculating averages
• You have five rocks, four with a mass of 50 g, and
one with a mass of 60 g. What is the average
mass of the rocks?
• Total mass = (4 x 50) + (1 x 60) = 260 g
• Average mass = (4 x 50) + (1 x 60) = 260 g
5
5
• Average mass = 4 x 50 + 1 x 60 = 260 g
5
5
5
California WEB
Calculating averages
• Average mass = 4 x 50 + 1 x 60 = 260 g
5 5
5
• Average mass = .8 x 50 + .2 x 60
• 80% of the rocks were 50 grams
• 20% of the rocks were 60 grams
• Average = % as decimal x mass +
% as decimal x mass +
% as decimal x mass +
California WEB
Isotopes
• Because of the existence of isotopes, the mass of a
collection of atoms has an average value.
• Average mass = ATOMIC WEIGHT
• Boron is 20% B-10 and 80% B-11.
That is, B-11 is 80 percent abundant on earth.
• For boron atomic weight
= 0.20 (10 amu) + 0.80 (11 amu) = 10.8 amu
Periodic Table
• Dmitri Mendeleev developed the
modern periodic table.
• Argued that element properties are
periodic functions of their atomic
weights.
• We now know that element
properties are periodic
functions of their
ATOMIC NUMBERS.
Atomic Mass
Magnesium has three isotopes.
78.99% magnesium 24 with
a mass of 23.9850 amu,
10.00% magnesium 25 with
a mass of 24.9858 amu, and
the rest magnesium 26 with
a mass of 25.9826 amu.
What is the atomic mass of
magnesium?
If not told otherwise,
the mass of the isotope is
the mass number in amu.
California WEB
Isotope
Percent
Abundance
Mg-24
78.99
23.9850 18.94575
Mg-25
10.00
24.9585
2.49585
Mg-26
11.01
25.9826
2.86068
Mass
24.304 amu
Atomic Mass
Calculate the atomic mass of copper if copper has two isotopes.
69.1% has a mass of 62.93 amu and the rest has a mass of
Percent
64.93 amu.
Isotope
Mass
Abundance
Cu-63
69.1
62.93
43.48463
Cu-65
30.9
64.93
20.06337
63.548
Average atomic mass (AAM)  (% " A" )(mass " A" )  (% " B" )(mass " B" )  ...
A.A.M.  (0.691)(62.93 amu)  (0.309)(64.93 amu)
A.A.M.  43.48463 amu  20.06337 amu
A.A.M.  63.548 amu for Copper
29
Cu
63.548
Protons
Neutrons
Electrons
Mass
number
Cu-65
A
B
29
C
A.
B.
C.
Argon
D
E
F
40
D.
E.
F.
Ba2+
56
G
H
I
G.
H.
I.
Given the average atomic mass of an element is 118.21 amu and it has
three isotopes (“A”, “B”, and “C”):
isotope “A” has a mass of 117.93 amu and is 87.14% abundant
isotope “B” has a mass of 120.12 amu and is 12.36% abundant
Find the mass of isotope “C”.
Show work for credit.
Extra Credit: What is a cation?
Protons
Neutrons
Electrons
Mass
number
Cu-65
A = 29
B = 36
29
C = 65
Argon
D = 18 E = 22
F = 18
40
Ba2+
56
G = 81 H = 54 I = 137
Given the average atomic mass of an element is 118.21 amu and it has
three isotopes (“A”, “B”, and “C”):
isotope “A” has a mass of 117.93 amu and is 87.14% abundant
isotope “B” has a mass of 120.12 amu and is 12.36% abundant
Find the mass of isotope “C”.
Show work for credit.
119.7932 amu
Extra Credit: What is a cation?
A positively charged atom. An atom that has lost a(n) electron(s).
Given the average atomic mass of an element is 118.21 amu and it has
three isotopes (“A”, “B”, and “C”):
isotope “A” has a mass of 117.93 amu and is 87.14% abundant
isotope “B” has a mass of 120.12 amu and is 12.36% abundant
Find the mass of isotope “C”.
Show work for credit.
Average Atomic Mass  (% " A" )(mass " A" )  (% " B" )(mass " B" )  (% " C" )(mass " C" )
118.21 amu  (0.8714)(117.93 amu)  (0.1236)(120.12 amu)  (0.005)(X amu)
118.21 amu  102.764202 amu  14.846832 amu  (0.005)(X amu)
0.598966  0.005 X amu
0.598966  0.005 X amu
0.005
0.005
X  119.7932 amu
I. Waves and Particles
• De Broglie’s Hypothesis
– Particles have wave characteristics
– Waves have particle characteristics
– λ = h/mn
• Wave-Particle Duality of Nature
• Waves properties are significant at small
momentum
Electrons as Waves
• Louis de Broglie (1924)
Louis de Broglie
~1924
– Applied wave-particle theory to electrons
– electrons exhibit wave properties
QUANTIZED WAVELENGTHS
Fundamental mode
200
Second Harmonic or First Overtone
200
150
150
150
100
100
100
50
50
50
0
0
0
- 50
- 50
- 50
-100
-100
-100
-150
-150
-150
-200
-200
-200
0
50
100
150
200
Standing Wave
200
0
50
100
150
200
0
Adapted from work by Christy Johannesson www.nisd.net/communicationsarts/pages/chem
50
100
150
200
Electrons as Waves
QUANTIZED WAVELENGTHS
L
n=4
L = 1 (l)
2
n=1
n=5
1 half-wavelength
L = 2 (l)
2
n=2
2 half-wavelengths
n=6
Forbidden
n = 3.3
L = 3 (l)
2
n=3
3 half-wavelengths
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electrons as Waves
Evidence: DIFFRACTION PATTERNS
VISIBLE LIGHT
Davis, Frey, Sarquis, Sarquis, Modern Chemistry 2006, page 105
ELECTRONS
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Dual Nature of Light
Waves can bend
around small obstacles…
…and fan out
from pinholes.
Particles effuse from pinholes
Three ways to tell a wave from a particle…
wave behavior
particle behavior
waves interfere
particle collide
waves diffract
particles effuse
waves are delocalized particles are localized
Quantum Mechanics
• Heisenberg Uncertainty Principle
– Impossible to know both the velocity and
position of an electron at the same time
g
Microscope
Electron
Werner Heisenberg
~1926
Quantum Mechanics
• Schrödinger Wave Equation (1926)
Erwin Schrödinger
~1926
– finite # of solutions  quantized energy levels
– defines probability of finding an electron
Ψ 1s 

1 Z 3/2 σ
π a0
e
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Mechanics
• Orbital (“electron cloud”)
– Region in space where there is 90%
probability of finding an electron
90% probability of
finding the electron
Electron Probability vs. Distance
Electron Probability (%)
40
30
20
10
0
0
50
100
150
Distance from the Nucleus (pm)
Orbital
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
200
250
Quantum Numbers
• Four Quantum Numbers:
– Specify the “address” of each electron
in an atom
UPPER LEVEL
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Numbers
Principal Quantum Number ( n )
Angular Momentum Quantum # ( l )
Magnetic Quantum Number ( ml )
Spin Quantum Number ( ms )
Relative Sizes 1s and 2s
1s
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 334
2s
Quantum Numbers
1. Principal Quantum Number ( n )
– Energy level
1s
– Size of the orbital
–
n2
= # of orbitals in
the energy level
2s
3s
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
1s orbital imagined as “onion”
Concentric spherical shells
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Shapes of s, p, and d-Orbitals
s orbital
p orbitals
d orbitals
Atomic Orbitals
s, p, and d-orbitals
A
s orbitals:
Hold 2 electrons
(outer orbitals of
Groups 1 and 2)
Kelter, Carr, Scott, , Chemistry: A World of Choices 1999, page 82
B
p orbitals:
Each of 3 pairs of
lobes holds 2 electrons
= 6 electrons
(outer orbitals of
Groups 13 to 18)
C
d orbitals:
Each of 5 sets of
lobes holds 2 electrons
= 10 electrons
(found in elements
with atomic no. of 21
and higher)
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Y21s
r
Y22s
r
r
Y23s
r
r
r
Distance from nucleus
(a) 1s
(b) 2s
(c) 3s
Quantum Numbers
y
y
z
x
z
x
px
y
z
x
pz
py
p-Orbitals
px
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 335
pz
py
y
y
z
x
z
x
s
2s
Mark Wirtz, Edward Ehrat, David L. Cedeno*
y
z
x
px
y
z
x
pz
2p (x, y, z)
py
carbon
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
Quantum Numbers
2. Angular Momentum Quantum # ( l )
– Energy sublevel
– Shape of the orbital
s
p
d
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
f
The azimuthal quantum number
Second quantum number l
is called the azimuthal quantum number
– Value of l describes the shape of the region of space
occupied by the electron
– Allowed values of l depend on the value of n and can
range from 0 to n – 1
– All wave functions that have the same value of both
n and l form a subshell
– Regions of space occupied by electrons in the same
subshell have the same shape but are oriented
differently in space
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
A Cross Section of an Atom
Rings of Saturn
n0
p+
1s
2s
2p
3s
3p
The first ionization energy level has only one sublevel (1s).
The second energy level has two sublevels (2s and 2p).
The third energy level has three sublevels (3s, 3p, and 3d).
Although the diagram suggests that electrons travel in circular orbits,
this is a simplification and is not actually the case.
Corwin, Introductory Chemistry 2005, page 124
3d
Quantum Numbers
• Orbitals combine to form a spherical shape.
2s
2px
2py
2pz
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Numbers
Principal
level
n=1
Sublevel
s
Orbital
n=2
s
p
px
py pz
n=3
s
p
px
py pz
d
dxy
dxz
• n = # of sublevels per level
• n2 = # of orbitals per level
• Sublevel sets: 1 s, 3 p, 5 d, 7 f
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dyz
dz2
dx2- y2
Maximum Capacities of Subshells
and Principal Shells
n
1
2
l
0
0
1
0
1
2
0
1
2
3
Subshell
designation
s
s
p
s
p
d
s
p
d
f
Orbitals in
subshell
1
1
3
1
3
5
1
3
5
7
Subshell
capacity
2
2
6
2
6
10
2
6
10 14
Principal shell
capacity
2
8
Hill, Petrucci, General Chemistry An Integrated Approach 1999, page 320
3
18
4
...n
32
...2n2
Quantum Numbers
3. Magnetic Quantum Number ( ml )
– Orientation of orbital
– Specifies the exact orbital within each sublevel
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The magnetic quantum number
Third quantum is ml, the magnetic quantum number
– Value of ml describes the orientation of the region
in space occupied by the electrons with respect to
an applied magnetic field
– Allowed values of ml depend on the value of l
– ml can range from –l to l in integral steps
ml = l, -l + l, . . . 0 . . ., l – 1, l
– Each wave function with an allowed combination of
n, l, and ml values describes an atomic orbital, a
particular spatial distribution for an electron
– For a given set of quantum numbers, each principal
shell contains a fixed number of subshells, and
each subshell contains a fixed number of orbitals
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
d-orbitals
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 336
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Principal Energy Levels 1 and 2
Quantum Numbers
4. Spin Quantum Number ( ms )
– Electron spin  +½ or -½
– An orbital can hold 2 electrons that spin in
opposite directions.
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Electron Spin: The Fourth Quantum Number
• When an electrically charged object spins, it produces a magnetic
moment parallel to the axis of rotation and behaves like a magnet.
• A magnetic moment is called electron spin.
• An electron has two possible orientations in an external magnetic
field, which are described by a fourth quantum number ms.
• For any electron, ms can have only two possible values, designated
+ (up) and – (down), indicating that the two orientations are opposite
and the subscript s is for spin.
• An electron behaves like a magnet that has one of two possible
orientations, aligned either with the magnetic field or against it.
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
Quantum Numbers
• Pauli Exclusion Principle
– No two electrons in an atom can have the
same 4 quantum numbers.
– Each electron has a unique “address”:
1. Principal #
2. Ang. Mom. #
3. Magnetic #
4. Spin #




energy level
sublevel (s,p,d,f)
orbital
electron
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Wolfgang Pauli
Allowed Sets of Quantum Numbers for Electrons in Atoms
Level n
1
l
0
0
Sublevel
Orbital ml
Spin ms
= +1/2
= -1/2
2
0
0
1
3
1
0
-1
0
0
1
1
0
-1
2
1
2
0
-1
-2
Feeling overwhelmed?
Read Section
5.10 - 5.11!
"Teacher, may I be excused? My brain is full."
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Electron Orbitals:
Electron
orbitals
Equivalent
Electron
shells
(a) 1s orbital
1999, Addison, Wesley, Longman, Inc.
(b) 2s and 2p orbitals
c) Neon Ne-10: 1s, 2s and 2p
What sort of covalent bonds
are seen here?
H
H
H
O
O
H
O
O
(b) O2
(a) H2
H
H
O
H
O
H
H
O
H
H
C
H
H
(c) H2O
H
H
(d) CH4
H
THIS SLIDE IS ANIMATED
IN FILLING ORDER 2.PPT
H = 1s1
1s
He = 1s2
1s
Li = 1s2 2s1
1s
2s
1s
2s
1s
2s
2px 2py 2pz
1s
2s
2px 2py 2pz
Be = 1s2 2s2
C = 1s2 2s2 2p2
S = 1s2 2s2 2p4
3s
3px 3py 3pz
H = 1s1
1s
e+1
He = 1s2
1s
e+2
e-
Coulombic attraction holds valence electrons to atom.
Be = 1s2 2s2
1s
2s
ee+4
e-
Coulombic attraction holds valence electrons to atom.
eValence electrons are shielded by the kernel electrons.
Therefore the valence electrons are not held as tightly in Be than in He.
26 electrons.
Iron has ___
Fe = 1s1 2s22p63s23p64s23d6
1s
2px 2py 2pz
2s
3s
3px 3py 3pz
6s
6p
4s
5d
3d
3d
3d
4f
32
5s
e-
e-
e-
+26
e-
e-
ee-
e-
ee-
e-
e-
4s
4p
3d
e-
e-
ee-
18
e-
e-
e-
ee-
4d
e-
ee-
5p
18
Arbitrary
Energy Scale
3s
3p
8
e-
e-
2s
2p
8
1s
2
NUCLEUS
3d
3d
Electron Configurations
Orbital Filling
Element
1s
2s
2px 2py 2pz
3s
Electron
Configuration
H
1s1
He
1s2
C
NOT CORRECT
1s22s1
Violates Hund’s
Rule
1s22s22p2
N
1s22s22p3
O
1s22s22p4
F
1s22s22p5
Ne
1s22s22p6
Na
1s22s22p63s1
Li
Electron Configurations
Orbital Filling
Element
1s
2s
2px 2py 2pz
3s
Electron
Configuration
H
1s1
He
1s2
Li
1s22s1
C
1s22s22p2
N
1s22s22p3
O
1s22s22p4
F
1s22s22p5
Ne
1s22s22p6
Na
1s22s22p63s1
Filling Rules for Electron Orbitals
Aufbau Principle: Electrons are added one at a time to the lowest
energy orbitals available until all the electrons of the atom
have been accounted for.
Pauli Exclusion Principle: An orbital can hold a maximum of two electrons.
To occupy the same orbital, two electrons must spin in opposite
directions.
Hund’s Rule: Electrons occupy equal-energy orbitals so that a maximum
number of unpaired electrons results.
*Aufbau is German for “building up”
Filling Rules for Electron Orbitals
Aufbau Principle: Electrons are added one at a time to the lowest
energy orbitals available until all the electrons of the atom
6s
6p
5d
4f
have been accounted for.
32
5s
5p
4d
18
Pauli Exclusion Principle: An orbital
can
hold
a
maximum
of
two
electrons.
4s
4p
3d
To occupy the same orbital, two electrons must spin in opposite
18
directions. Arbitrary
North
South
3s
3p
Energy Scale
8
-
-
2s
2p
Hund’s Rule: Electrons occupy equal-energy
orbitals so that a maximum
number of unpaired electrons results.
8
1s
*Aufbau is German for “building up”
S
N
NUCLEUS
2
Spin Quantum Number, ms
North
Electron aligned with
magnetic field,
South
N
S
Electron aligned against
magnetic field,
ms =its
-½
ms = +behaves
½
The electron
as if it were spinning about an axis through
center.
This electron spin generates a magnetic field, the direction of which depends
on the direction of the spin.
Brown, LeMay, Bursten, Chemistry The Central Science, 2000, page 208
Energy Level Diagram of a Many-Electron Atom
6s
6p
5d
4f
32
5s
5p
4d
18
4s
4p
3d
18
Arbitrary
Energy Scale
3s
3p
8
2s
2p
8
1s
2
NUCLEUS
O’Connor, Davis, MacNab, McClellan, CHEMISTRY Experiments and Principles 1982, page 177
Maximum Number of Electrons
In Each Sublevel
Maximum Number of Electrons In Each Sublevel
Sublevel
Number of Orbitals
Maximum Number
of Electrons
s
1
2
p
3
6
d
5
10
f
7
14
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 146
Quantum Numbers
n
shell
1, 2, 3, 4, ...
l
subshell
0, 1, 2, ... n - 1
ml
orbital
- l ... 0 ... +l
ms
electron spin
+1/2 and - 1/2
Order in which subshells are filled
with electrons
1s
2s
2p
3s
3p
3d
4s
4p
4d
4f
5s
5p
5d
5f
6s
6p
6d
7s
2
2
6
2
6
2
10
6
2
10
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d …
4f
Sublevels
4d
Energy
6d
5f
7s
6p
5d
4f
6s
5p
4d
5s
4p
3d
4s
3p
6d
7s
6p
5d
6s
4f
n=3
5p
4p
3d
4s
3p
3s
4d
5s
4p
3d
4s
3p
3s
2p
2s
5f
Energy
n=4
2p
3s
2p
n=2
2s
2s
1s
1s
n=1
1s
4f
Sublevels
4d
s
p
s
d
p
s
n=4
f
d
p
Energy
s
n=3
4p
3d
4s
3p
3s
1s22s22p63s23p64s23d104p65s24d10…
2p
n=2
2s
n=1
1s
Filling Rules for Electron Orbitals
Aufbau Principle: Electrons are added one at a time to the lowest
energy orbitals available until all the electrons of the atom
have been accounted for.
Pauli Exclusion Principle: An orbital can hold a maximum of two electrons.
To occupy the same orbital, two electrons must spin in opposite
directions.
Hund’s Rule: Electrons occupy equal-energy orbitals so that a maximum
number of unpaired electrons results.
*Aufbau is German for “building up”
Energy Level Diagram of a Many-Electron Atom
6s
6p
5d
4f
32
5s
5p
4d
18
4s
4p
3d
18
Arbitrary
Energy Scale
3s
3p
8
2s
2p
8
1s
2
NUCLEUS
O’Connor, Davis, MacNab, McClellan, CHEMISTRY Experiments and Principles 1982, page 177
Electron
capacities
Copyright © 2006 Pearson Benjamin Cummings. All rights reserved.
32
32
18
18
2
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
8
8
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Hydrogen
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
H = 1s1
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Helium
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
He = 1s2
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Lithium
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
Li = 1s22s1
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Carbon
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
C = 1s22s22p2
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Nitrogen
4f
Bohr Model
N
Hund’s Rule “maximum
number of unpaired
orbitals”.
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
N = 1s22s22p3
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Fluorine
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
F = 1s22s22p5
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Aluminum
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
Al = 1s22s22p63s23p1
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Argon
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
Ar = 1s22s22p63s23p6
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
Iron
4f
Bohr Model
N
2s
2p
1s
Electron Configuration
Fe = 1s22s22p63s23p64s23d6
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
Fe La
Arbitrary Energy Scale
Energy Level Diagram
6s
6p
5d
5s
5p
4d
4s
4p
3d
3s
3p
4f
Lanthanum
Bohr Model
N
2s
2p
1s
Electron Configuration
NUCLEUS
H He Li C N Al Ar F
CLICK ON ELEMENT TO FILL IN CHARTS
La = 1s22s22p63s23p64s23d10
Fe La 4s23d104p65s24d105p66s25d1
Shorthand Configuration
A neon's electron configuration (1s22s22p6)
B
third energy level
[Ne] 3s1
C
D
one electron in the s orbital
orbital shape
Na = [1s22s22p6] 3s1
electron configuration
Shorthand Configuration
Element symbol
Electron configuration
Ca
[Ar] 4s2
V
[Ar] 4s2 3d3
F
[He] 2s2 2p5
Ag
[Kr] 5s2 4d9
I
[Kr] 5s2 4d10 5p5
Xe
[Kr] 5s2 4d10 5p6
Fe
Sg
22p64s
[He] 2s[Ar]
3s223d
3p664s23d6
[Rn] 7s2 5f14 6d4
General Rules
• Pauli Exclusion Principle
– Each orbital can hold TWO electrons with
opposite spins.
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Wolfgang Pauli
General Rules
6d
Aufbau Principle
7s
6p
5d
– Electrons fill the
lowest energy
orbitals first.
6s
4d
3p
5f
7s
6p
5d
6s
5p
5s
4p
4s
6d
4f
5p
Energy
– “Lazy Tenant
Rule”
5f
4d
5s
3d
4p
3d
4s
3p
3s
3s
2p
2p
2s
2s
1s
1s
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4f
General Rules
• Hund’s Rule
– Within a sublevel, place one electron
per orbital before pairing them.
– “Empty Bus Seat Rule”
WRONG
RIGHT
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8
O
Notation
15.9994
• Orbital Diagram
O
8e-
1s
2s
• Electron Configuration
2
2
4
1s 2s 2p
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
2p
16
Notation
S
32.066
• Longhand Configuration
S 16e- 1s2 2s2 2p6 3s2 3p4
Core Electrons
Valence Electrons
• Shorthand Configuration
S
16e
2
4
[Ne] 3s 3p
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Periodic Patterns
s
1
2
3
4
5
6
7
p
1s
2s
f
2p
3s
d (n-1)
3p
4s
3d
4p
5s
4d
5p
6s
5d
6p
7s
6d
7p
6
(n-2) 7
4f
5f
1s
Periodic Patterns
• Period #
– energy level (subtract for d & f)
• A/B Group #
– total # of valence e-
• Column within sublevel block
– # of e- in sublevel
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Periodic Patterns
• Example - Hydrogen
1
2
3
4
5
6
7
1
1s
1st Period
1st column
of s-block
s-block
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Periodic Patterns
• Shorthand Configuration
– Core electrons:
• Go up one row and over to the Noble Gas.
– Valence electrons:
• On the next row, fill in the # of e- in each sublevel.
1
2
3
4
5
6
7
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32
Periodic Patterns
• Example - Germanium
1
2
3
4
5
6
7
[Ar]
2
4s
10
3d
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2
4p
Ge
72.61
Stability
• Full energy level
• Full sublevel (s, p, d, f)
• Half-full sublevel
1
2
3
4
5
6
7
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The Octet Rule
Atoms tend to gain, lose, or share electrons
until they have eight valence electrons.
This fills the valence
shell and tends to give
the atom the stability
of the inert gasses.
8
ONLY s- and p-orbitals are valence electrons.
Stability
• Electron Configuration Exceptions
– Copper
EXPECT:
[Ar] 4s2 3d9
ACTUALLY:
[Ar] 4s1 3d10
– Copper gains stability with a full
d-sublevel.
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Stability
• Electron Configuration Exceptions
– Chromium
EXPECT:
[Ar] 4s2 3d4
ACTUALLY:
[Ar] 4s1 3d5
– Chromium gains stability with a half-full
d-sublevel.
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Electron Filling in Periodic Table
s
s
p
1
2
d
3
4
K
4s1
Ca
4s2
Sc
3d1
Ti
3d2
4f
Energy
n=4
n=3
V
3d3
Cr
3d54
Mn
3d5
Fe
3d6
Co
3d7
Ni
3d8
Cu
9
3d
3d10
Cr
Cu
4s13d5
4s13d10
Zn
3d10
Ga
4p1
Ge
4p2
As
4p3
Se
4p4
Br
4p5
Kr
4p6
4d
4p
3d
4s
3p
3s
Cr
4s13d5
4s
3d
2p
n=2
2s
n=1
Cu
1s
4s13d10
4s
3d
Stability
• Ion Formation
– Atoms gain or lose electrons to become more
stable.
– Isoelectronic with the Noble Gases.
1
2
3
4
5
6
7
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Stability
• Ion Electron Configuration
– Write the e- configuration for the closest
Noble Gas
• EX: Oxygen ion  O2-  Ne
O2-
10e-
[He] 2s2 2p6
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28
Orbital Diagrams for Nickel
1s
2
2s
2
6
2p
3s
2
6
3p
2
4s
3d
8
Excited State
1s 2 2s 2
2p 6
3s 2
3p6
4s1
3d 9
Pauli Exclusion
1s
2s
2p
3s
3p
4s
3d
Hund’s Rule
1s
2s
2p
3s
3p
4s
3d
Ni
58.6934
28
Orbital Diagrams for Nickel
1s
2
2s
2
6
2p
3s
2
6
3p
2
4s
3d
8
Excited State
1s
2
2s
2
2p
6
3s
2
6
3p
4s
1
3d
9
VIOLATES Pauli Exclusion
1s
2s
2p
3s
3p
4s
3d
VIOLATES Hund’s Rule
1s
2s
2p
3s
3p
4s
3d
Ni
58.6934
Write out the complete electron configuration for the following:
1) An atom of nitrogen
2) An atom of silver
3) An atom of uranium (shorthand)
POP
QUIZ
Fill in the orbital boxes for an atom of nickel (Ni)
1s
2s
2p
3s
3p
4s
3d
Which rule states no two electrons can spin the same direction in a single orbital?
Extra credit: Draw a Bohr model of a Ti4+ cation.
Ti4+ is isoelectronic to Argon.
Answer Key
Write out the complete electron configuration for the following:
1) An atom of nitrogen 1s22s22p3
1s22s22p63s23p64s23d104p65s24d9
2) An atom of silver
3) An atom of uranium (shorthand)
[Rn]7s26d15f3
Fill in the orbital boxes for an atom of nickel (Ni)
1s
2s
2p
3s
3p
4s
3d
Which rule states no two electrons can spin the same direction in a single orbital?
Pauli exclusion principle
Extra credit: Draw a Bohr model of a Ti4+ cation.
Ti4+ is isoelectronic to Argon.
n=
22+
n
Electron Configurations and the
Periodic Table
Orbitals Being Filled
1
Periods
1
1s
8
Groups
2
3
4
5
2
2s
2p
3
3s
3p
4
4s
3d
4p
5
5s
4d
5p
6
6s
La
5d
6p
7
7s
Ac
6d
6
7 1s
4f
Lanthanide series
5f
Actinide series
Electron Filling in Periodic Table
s
p
1
2
d
3
4
5
6
*
7
W
f
*
W
s
s
s
1
H
p
H
He
1
2
1
2
3
Li
Be
B
C
N
O
F
Ne
3
4
5
6
7
8
9
10
Al
Si
P
S
Cl
Ar
13
14
15
16
17
18
Na Mg
11
4
K
19
5
7
12
Ca Sc
Ti
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
Kr
23
24
35
36
I
Xe
53
54
20
21
22
Rb Sr
Y
Zr Nb Mo Tc Ru Rh Pd Ag Cd
In
39
40
41
42
49
Hf
Ta
W
72
73
74
37
6
d
38
Cs Ba
55
56
Fr
Ra
87
88
*
W
25
43
26
44
Re Os
75
76
27
28
29
30
47
48
31
45
46
Ir
Pt Au Hg
Tl
77
78
81
79
80
32
33
34
Sn Sb Te
50
51
Pb Bi
82
83
52
Po At Rn
84
85
86
Rf Db Sg Bh Hs Mt
104
105
106
107
108
109
f
*
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
57
W
58
59
Ac Th Pa
89
90
91
60
U
92
61
62
63
64
65
66
Np Pu Am Cm Bk Cf
93
94
95
96
97
98
67
68
69
70
71
Es Fm Md No Lr
99
100
101
102
103
Electron Filling in Periodic Table
s
s
1
H
p
H
He
1s1
1s2
1s1
2
3
4
5
6
7
Li
Be
B
C
N
O
F
Ne
2s1
2s2
2p1
2p2
2p3
2p4
2p5
2p6
Al
Si
P
S
Cl
Ar
3p1
3p2
3p3
3p4
3p5
3p6
Na Mg
d
3s1
3s2
K
Ca Sc
Ti
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
Kr
4s1
4s2
3d1
3d2
3d3
3d5
3d10
4p1
4p2
4p5
4p6
Rb Sr
Y
Zr Nb Mo Tc Ru Rh Pd Ag Cd
In
Sn Sb Te
I
Xe
5s1
4d1
4d2
4d4
4d5
4d6
4d7
4d8
4d10
4p1
5p1
5p2
5p5
5p6
Hf
Ta
W
Re Os
Ir
Pt Au Hg
Tl
Pb Bi
Po At Rn
5d2
5d3
5d4
5d5
5d7
5d9
6p1
6p2
6p4
5s2
Cs Ba
6s1
6s2
Fr
Ra
7s1
7s2
*
W
3d5
3d6
5d6
3d7
3d8
3d10
4d10
5d10
5d10
4p3
5p3
6p3
4p4
5p4
6p5
6p6
Rf Db Sg Bh Hs Mt
6d2
6d3
6d4
6d5
6d6
6d7
f
*
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
5d1
W
4f2
4f3
4f4
Ac Th Pa
U
6d1
5f3
6d2
5f2
4f5
4f6
4f7
4f7
4f9
4f10
Np Pu Am Cm Bk Cf
5f4
5f6
5f7
5f7
5f8
5f10
4f11
4f12
4f13
4f14
4f114
Es Fm Md No Lr
5f11
5f14
5f13
5f14
5f14
Electron Filling in Periodic Table
s
s
p
1
2
d
3
4
K
4s1
Ca
4s2
Sc
3d1
Ti
3d2
4f
Energy
n=4
n=3
V
3d3
Cr
3d54
Mn
3d5
Fe
3d6
Co
3d7
Ni
3d8
Cu
9
3d
3d10
Cr
Cu
4s13d5
4s13d10
Zn
3d10
Ga
4p1
Ge
4p2
As
4p3
Se
4p4
Br
4p5
Kr
4p6
4d
4p
3d
4s
3p
3s
Cr
4s13d5
4s
3d
2p
n=2
2s
n=1
Cu
1s
4s13d10
4s
3d
Electron Configurations
of First 18 Elements:
Hydrogen
1H
Helium
2He
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
3Li
4Be
5B
6C
7N
8O
9F
10Ne
Sodium
Magnesium
Aluminum
Silicon
Phosphorous
Sulfur
Chlorine
Argon
11Na
12Mg
13Al
14Si
15P
16S
17Cl
18Ar
Electron Dot Diagrams
Group
1A
1
2A
2
3A
13
4A
14
5A
15
6A
16
7A
17
H
8A18
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Ga
Ge
As
Se
Br
Kr
s1
s2
s2p1
s2p2
s2p3
s2p4
= valence electron
s2p5
s2p6
V. Outer Level e-’s
• Valence electrons
• Usually involved in chemical
changes
• Dot diagram
–Symbol represents the nucleus
–Dots represent the outer e-’s
First Four Energy Levels
n=4
Energy
n=3
n=2
n=1
Sublevels
Sublevel designation
4s
4p
Four sublevels
3s
4d
3p
3d
Principal
level 3
Three sublevels
2s
2p
Two sublevels
1s
One sublevel
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 334
Principal
level 4
4f
Principal
level 2
Principal
level 1
Principal Level 2 Divided
2p sublevel
2s sublevel
2s
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 334
2px
2py
2pz
4f
Sublevels
4d
Principal
level 4
Four sublevels
Principal
level 3
Three sublevels
One sublevel
Principal
level 2
Principal
level 1
Energy
Two sublevels
n=4
n=3
4p
3d
4s
3p
3s
2p
n=2
2s
n=1
1s
Metals, Nonmetals, Metalloids
Metals and Nonmetals
1
2
3
H
He
1
2
Li
Be
B
C
3
4
5
Na Mg
11
4
K
19
5
7
Ca Sc
O
F
Ne
6
7
8
9
10
Al
Si
P
S
Cl
Ar
13
14
15
16
17
18
Ti
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
Kr
23
24
35
36
I
Xe
53
54
20
21
22
Rb Sr
Y
Zr Nb Mo Tc Ru Rh Pd Ag Cd
In
39
40
41
42
49
Hf
Ta
W
72
73
74
37
6
12
N
38
Cs Ba
55
56
Fr
Ra
87
88
*
W
Nonmetals
25
26
27
28
29
30
METALS
43
44
Re Os
75
76
47
45
46
Ir
Pt Au Hg
Tl
77
78
81
79
48
31
80
32
33
34
Sn Sb Te
50
51
Pb Bi
82
83
52
Po At Rn
84
85
86
Rf Db Sg Bh Hs Mt
104
105
106
107
108
Metalloids
109
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
57
58
59
Ac Th Pa
89
90
91
60
U
92
61
62
63
64
65
66
Np Pu Am Cm Bk Cf
93
94
95
96
97
98
67
68
69
70
71
Es Fm Md No Lr
99
100
101
102
103
Metals, Nonmetals, & Metalloids
1
Nonmetals
2
3
4
5
Metals
6
7
Metalloids
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 349
Periodic Table
Isotopes of Magnesium
12e-
12e12p+
12n0
Atomic symbol
24
12
Mg
12p+
13n0
25
12
Mg
12e12p+
14n0
26
12
Mg
Number of protons
12
12
12
Number of electrons
12
12
12
Mass number
24
25
26
Number of neutrons
12
13
14
Mg-24
Mg-25
Mg-26
Isotope Notation
Timberlake, Chemistry 7th Edition, page 64
Isotopes of Hydrogen
Protium
1
p+
Deuterium
1 e-
1
H
1
(ordinary hydrogen)
H-1
Ralph A. Burns, Fundamentals of Chemistry 1999, page 100
1 p+
1n
2
H
1
(heavy hydrogen)
H-2
Tritium
1 e-
1 p+
2n
3
1
1 e-
H
(radioactive hydrogen)
H-3
Isotopes of Hydrogen
• Protium (H-1)
1 proton, 0 neutrons, 1 electron
most abundant isotope
1 p+
1 e-
1 p+
1n
1 e-
1 p+
2n
1 e-
• Deuterium (H-2)
1 proton, 1 neutron, 1 electron
used in “heavy water”
• Tritium (H-3)
1 proton, 2 neutrons, 1 electron
radioactive
Isotopes of Three Common Elements
Mass
Element
Carbon
Chlorine
Silicon
Symbol
Mass (amu)
Fractional
Abundance
Number
12
6
C
12
12 (exactly)
99.89%
13
6
C
13
13.003
1.11%
35
17
Cl
35
34.969
75.53%
37
17
Cl
37
36.966
24.47%
28
29
30
27.977
28.976
29.974
28
14
29
14
Si
Si
30
Si
14
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 110
92.21%
4.70%
3.09%
Average
Atomic
Mass
12.01
35.45
28.09
Radioisotopes
• Radioactive isotopes
• Many uses
– Medical diagnostics
– Optimal composition of
fertilizers
– Abrasion studies in engines and
tires
Radioisotope is injected
into the bloodstream to
observe circulation.
Half-Life of Isotopes
Half-Lives and Radiation of Some Naturally Occurring Radioisotopes
Isotope
Half-Life
Radiation emitted
Carbon-14
5.73 x 103 years
b
Potassium-40
1.25 x 109 years
b, g
Radon-222
3.8 days
a
Radium-226
1.6 x 103 years
a, g
Thorium-230
7.54 x 104 years
a, g
Thorium-234
24.1 days
b, g
Uranium-235
7.0 x 108 years
a, g
Uranium-238
4.46 x 109 years
a
Atomic Structure
• ATOMS
– Differ by number of protons
• IONS
– Differ by number of electrons
• ISOTOPES
– Differ by number of neutrons
Formation of Cation
sodium atom
Na
sodium ion
Na+
ee-
e-
e-
e-
e-
ee-
e-
11p+
ee-
loss of
one valence
electron
e-
e-
11p+
e-
e-
e-
e-
e-
e-
e-
e-
Formation of Anion
chlorine atom
Cl
e-
egain of
one valence
electron
ee-
e-
e-
chloride ion
Cl1e-
eee-
e-
e-
e-
e-
ee-
e-
17p+
17p+
e-
e-
e-
e-
ee-
e-
e-
ee-
e-
e-
e-
e-
e-
ee-
e-
e-
Formation of Ionic Bond
chloride ion
Cl1-
sodium ion
Na+
e-
e-
ee-
e-
e-
e-
e-
e-
e-
e-
e-
11p+
e-
e-
e-
e-
e-
e-
17p+
e-
e-
e-
e-
e-
e-
ee-
e-
e-
Ionic Bonding
NaCl
n=3
-
n=2
n=3
-
-
-
-
-
-
-
Na
[Ne]3s1
-
-
-
+
-
-
-
-
-
-
-
-
-
Cl
[Ne]3s23p5
-
-
-
Na+
[Ne]
-
-
-
Cl[Ne]3s23p6
Transfer of electrons to achieve a stable octet (8 electrons in valence shell).
Covalent Bonding
n=2
-
-
-
-
n=1
-
-
-
-
+
-
-
-
-
-
-
-
-
-
-
-
-
-
O
[He]2s22p4
-
O
[He]2s22p4
O2
Sharing of electrons to achieve a stable octet (8 electrons in valence shell).
Diatomic Elements, 1 and 7
H2
N2 O2 F2
Cl2
Br2
F2
Newton’s First Law of Motion (Law of Inertia)
Object at rest tends to
stay at rest, and object
in motion tends to stay
in motion at constant
velocity unless object
is acted upon by an
unbalanced, external
force.
inertia  mass
Resources - Atomic Structure
Objectives
General Chemistry PP
Worksheet - vocabulary
Worksheet - development of atomic theory
Worksheet - atomic number and mass number
Worksheet - ions and subatomic particles
Lab - isotopes
Worksheet - orbital diagrams
Worksheet - electron configuration
Episode 6 - Atom
Worksheet - light problems
Worksheet - half-life
Textbook - questions
Outline (general)