Atomic Structure: Pre-Assess
1. Illustrate an atom identifying the location of
its subatomic particles
2. What is an atom’s atomic number?
3. What is an atom’s mass number?
4. What is atomic mass?
5. What is an isotope?
Atoms
What are we going to study about the atom?
•History
•Structure
•Properties
•Forces
Atomic Structure
Subatomic
Particle
symbol
charge Mass (g)
mass
(amu)
proton
p+
+1
1.674 x 10 -24
1
electron
e-
-1
9.11 x 10-28
0
neutron
n0
0
1.675 x 10 -24
1
Distinguishing Atoms
education.jlab.org
• What distinguishes one element’s atom from another
element’s atom? number of protons
What distinguishes each element below from one another?
Distinguishing Atoms
Atomic number
• The number of protons within an atom’s nucleus.
• An atom’s I.D.
• Atoms of the same element always have the same
number of protons.
• What do you notice about the atomic numbers on
the periodic table? increase by one as you move
from left to right across each row.
An Atom’s Mass
Mass number :
• The mass of a single atom.
• Sum of the p+ and n0 within an atom.
• Unit: atomic mass unit (amu)
• The mass number is NOT the same as Atomic Mass
Neutral Atoms
• Most matter in nature is neutral.
(Doesn’t shock us!)
• This means the atoms making up the matter is
neutral. 
• What are the two charged subatomic particles?
protons = electrons in neutral atoms
Bell Ringer
1. What is an isotope?
2. What is a similarity and difference between
neutral C-12 and C-14 atoms?
3. Illustrate the location and amount of each
subatomic particle in a neutral C-14 atom.
Chem I: Homework
1. Calculate subatomic particles in each set of isotopes and
illustrate each isotope with correct location and number of
subatomic particles.
a. Li-6 and Li-7
b. H-1 and H-2
c. O-16 and O-17
d. B-10 and B-11
2. Do isotopes of the same element have similar chemical and
physical properties? Explain your answer.
3. Research and state the difference between the following
atomic structure terms: mass number and atomic mass.
*Record answers on separate sheet.
Isotopes and Atomic Mass
Atomic mass:
• The average mass of all the element’s isotopes
present within a naturally occurring sample of matter
• Weighted average mass. (unequal distribution of
isotopes in sample of matter)
• Located on the periodic table.
How do you calculate atomic mass?
1. Multiply the mass # of each isotope by its natural
abundance ( common occurrence) in decimal form.
2. Add all the isotopes products together.
Kandium Lab
Purpose:
• To analyze isotopes of Kandium and calculate its
atomic mass.
Data:
• Must show work for credit.
• Don‘t forget to include units.
Conclusion/Post-Lab Sections:
• Complete after the lab or homework
Atomic Model and Properties
• If most of the atom is empty space, why doesn’t
matter (atoms) pass through one another?
• What keeps the protons from leaving the nucleus
and being drawn towards the electrons?
Atomic Properties
If most of the atom is empty space, why doesn’t
matter pass through one another?
spiff.rit.edu
Atomic Forces
• Electrostatic Forces :
- Forces between charged
particles.
Types of electrostatic forces:
• Nuclear Forces:
Forces that hold p+ and n0
together in nucleus.
Atomic Forces
• Electrostatic Forces :
- Forces between charged
particles.
Types of electrostatic forces:
a. Attractive: (p+ and e-)
b. Repulsion: (p+ and p+
e- and e-)
• Nuclear Forces:
Forces that holds p+ and n0
together in nucleus.
Gallery Walk Slip: History of the Atom
• Who is given credit for the earliest model of the
because he applied the scientific method?
• What did Thomson’s model contribute to the atom?
• What did Rutherford’s model contribute to the atom?
• What did Bohr’s model contribute to the atom?
• What did Schrodinger’s (current) model contribute to the
atom?
Atomic Model and Properties
Homework:
• If most of the atom is empty space, why doesn’t
matter (atoms) pass through one another?
• What keeps the protons from leaving the nucleus
and being drawn towards the electrons?
Chem I (5th): 10/24
Infinite Campus Update:
• Kandium Lab (28pts.)
Objectives:
• I can understand and apply the history of the
atom with models.
• I can identify atomic forces and understand
their importance in the preservation of the
atom.
Homework:
• Atomic Structure Study Guide
ICP : 10/24
Infinite Campus Update:
• Kandium Lab (28pts.)
• Isotope and Atomic Mass worksheet (10pts.)
Objectives:
• I can understand and apply the history of the
atom with models.
• I can identify atomic forces and understand
their importance in the preservation of the
atom.
Homework:
• Atomic Structure Study Guide
Gallery Walk Slip: History of the Atom
1. Who is given credit for the earliest model of the atom
because he applied the scientific method?
2. What did Thomson’s model contribute to the atom?
3. What did Rutherford’s model contribute to the atom?
4. What did Bohr’s model contribute to the atom?
5. What did Schrodinger’s (current) model contribute to the
atom?
History of the Atom
•Great Thinkers (2,000yrs. Ago)
•Age of Reason and Thought
•Democritus vs. Aristotle view on the
make-up of matter.
Democritus(400b.c.)
Greek
Philosopher
1) Observed matter to be
made up of atoms.
2) Atoms are the smallest
form of matter.
3. Atoms cannot be broken
down.
3) The types of atoms in
matter determine its
properties.
4. Couldn’t prove with
scientific evidence-so
most did not believe.
Aristotle: Greek Philosopher (300b.c.)
•
Aristotle observed matter to be
made from four things:
earth, water, air, and fire
• Most popular because his
explanation of what matter was
composed of could be observed.
John Dalton’s Atomic Model
• English school teacher
• Proved Democritus atoms
hypothesis using the
scientific method.
• His conclusions produced:
Dalton’s Atomic Theory
Dalton’s Atomic Theory
1. Atoms are the building blocks of all matter.
2. Atoms cannot be subdivided.
3. Each element has the same kind of atoms.
4. A compound is composed of two or more atoms
chemically combined in a fixed amount. Ex. NaCl
5. Atoms cannot be created or destroyed just rearranged
during chemical reactions.
Thomson’s Cathode Tube Experiment
l-esperimento-piu-bello-della-fisica.bo.imm.c...
Subatomic Particle: Electron
J.J. Thomson (pg. 105)
• 1897 discovered electrons in gas atoms using a
cathode ray tube.
• Determined electrons have a negative charge.
• Electrons have the same charge in all atoms.
Chem I: 10/24
Infinite Campus Update:
• Kandium Lab (28pts.)
• Atomic Model Quiz (5pts.)
Objectives:
• I can understand and apply the history of the
atom with models.
• I can identify atomic forces and understand
their importance in the preservation of the
atom.
Homework:
• Atomic Structure Study Guide(required)
J. J Thomson’s Plum Pudding Model
• If atoms are made of electrons how come most
matter does not shock us?
• Atoms must have positive particles, too.
• He proposed the Plum Pudding Atomic Model
•
An atom is
equally made up
of positive and
negative particles.
What is the name of this atomic model?
Rutherford’s Gold Foil Experiment
Rutherford’s Gold Foil Experiment
His Conclusion :
•Most of the atom is empty space
red laser (red line) path did not change
the majority of the experiments.
•Small dense region composed of
(+) charged particles, nucleus,
because a few times red laser’s path
changed significantly.
Rutherford’s Nuclear Atomic Model
Subatomic Particle: Neutron
•What keeps the protons within the nucleus ?
(Like particles repel each other)
•1932 - James Chadwick discovers that the
nucleus also has neutral particles present. He
called them neutrons.
Bohr’s Model of the Atom
•Electrons travel in fixed, circular paths
around the nucleus.
•Each path has a specific energy
requirement.
•These circular paths are called energy
levels.
•Limited number of electrons on each
energy level. (2n2 Rule)
http://micro.magnet.fsu.edu/
Current Atomic Model
Erwin Schrodinger
blogs.stsci.edu
science.howstuffworks.com
Current Atomic Model
Electrons do not travel in fixed paths around
the nucleus
Electrons constantly move to different
energy levels in the electron cloud.
Direction of movement is dependent
upon how much energy an electron has.
Observed several different paths electrons
can take around the nucleus.
Types of electron paths around nucleus
Atomic Model and Properties
• If most of the atom is empty space, why doesn’t
matter (atoms) pass through one another?
• What keeps the protons from leaving the nucleus
and being drawn towards the electrons?
Atomic Properties
If most of the atom is empty space, why doesn’t
matter pass through one another?
spiff.rit.edu
Atomic Model and Properties
• If most of the atom is empty space, why doesn’t
matter (atoms) pass through one another?
• What keeps the protons from leaving the nucleus
and being drawn towards the electrons?
Atomic Forces
1. Electrostatic Forces :
- Forces between charged
particles.
Types of electrostatic forces:
2. Nuclear Forces:
Forces that hold p+ and n0
together in nucleus.
*Which force is stronger?
Chem I : 10/25
Due:
• Evolution of Atom (14pts.)
Objectives:
• Review concepts pertaining to Atomic
Structure via gallery walk.
• “The Space Between Atom” (youtube video)
Homework:
• Review notes, labs, quizzes, and complete
study guide.
• Band of Stability Graph Wksht.
Gallery Walk
• Will review atomic structure concepts via
gallery walk. After record answer on white
board record on notebook paper.
• Assess peers answers and make corrections
when needed.
Atomic Structure Study Guide
Matter Does Not Touch Other Matter
• “The Space Between Atoms” (youtube video)
Exit Slip
1. Give a similarity and difference between
Bohr’s model and Schrodinger’s model of the
atom. Be specific.
2. a. Identify and distinguish between the two
types of forces within an atom.
b. Why doesn’t the atom collapse on itself
since it has positive and negative particles in
it?
Atomic Mass
(Element’s average mass)
• Carbon (C) has two isotopes:
Carbon-12 has a natural abundance = 98.89%
Carbon-13 has a natural abundance = 1.11%
Carbon’s atomic mass=
(12 x 0.9889) + ( 13x0.0111) = 12.011 amu
= 12 amu (2 sig. figures)
Atomic Mass Unit (amu)
• Scientist needed an easier value to describe an
atom’s mass #.
• Use a reference isotope as a standard.
• Carbon-12 was chosen as the reference isotope
because of its natural abundance and strong
stability.
• Carbon’s atomic mass unit = 12 amu
• Atomic mass unit (amu)= 1/12 the mass of a
Carbon-12 atom.
• Compare atom’s mass with Carbon
Periodic Table
• Atomic # = The elements are arranged in
numerical order based on the number of
protons present within their atom.
• Metal vs. Non-metal vs. Metalloids
• Periods vs. Groups
Periodic Table:
Metals
• Metals are the majority of elements on the
periodic table.
• They are every thing left of the metalloids.
• Some metals are extremely reactive and some
don’t react easily.
• Transition metals are elements that form a
bridge between the elements on the left and
right sides of the periodic table.
Periodic Table: Non-metals
• Non-metals are elements that are poor
conductors of heat and electric current.
• Because non metals have low boiling points,
many non metals are gases at room
temperature.
• Fun fact-All the gases in the periodic table are
non metals
Periodic Table: Metalloids
• Metalloids are elements with properties that fall
between those of metals and non-metals.
• Metals are good conductors of electric current and
non-metals are poor conductors of electric current.
• Metalloids ability to conduct electric current varies
with temperature.
• Examples of metalloids:
– Boron, silicon, germanium, arsenic, antimony, polonium,
and astatine.
Periodic Table:
Periods (rows)
Periodic Table:
Groups
• Each column in the periodic table;;
• The elements of the group have similar properties &
Electron configurations;;
• The electron configuration determines its chemical
properties;;
• Properties of elements repeat in a predictable way
when atomic numbers are used to arrange elements
into groups;;
• The pattern of repeating properties is the periodic
law;;
An Element’s Isotopes
• Isotopes= atoms with different number of
neutrons in their nucleus.
• Elements can have several isotopes
• Mass # changes. (varied # neutrons)
• Atomic # stays the same (# of protons)
• Chemical properties of an element’s
isotopes are the same because their # of
protons and electrons are the same.
Atomic Mass
Element’s average mass
• Atomic mass= average mass of all the
naturally occurring isotopes of an element.
• Multiply the mass number of each isotope by
its natural abundance (decimal form) and
then add all the isotopes products together.
Atomic Mass
(Element’s average mass)
• Carbon (C) has two stable isotopes:
Carbon-12 has a natural abundance = 98.89%
Carbon-13 has a natural abundance = 1.11%
Carbon’s atomic mass=
(12 x 0.9889) +13x0.0111) = 12.011 amu
Bell Ringer: 9/9/09
• 1. What is an isotope?
• 2. How many isotopes did Kandium have?
• 3. Did each of Kandium’s isotope have the same
mass?
• 4. What two values did you need to calculate
Kandium’s atomic mass?
• 5. After you calculated Kandium’s atomic mass
what other value did you need to determine its
atomic composition (p+,e-, n0)
Element’s Atomic Mass
• Element’s atomic mass = average mass
calculated from its isotopes.
• Isotopes : mass # (amu) and relative abundance
Ex. Calculate Nitrogen’s atomic mass:
Nitrogen-14 has a natural abundance 99.63%
Nitrogen-15 has a natural abundance 0.37%
Calculating Kandium’s
Atomic Mass
•
•
•
•
M&M –
ReesiumSkittliumKa atomic mass=
Kandium Lab
• Realistically, we can determine an
element’s isotopes mass(g) by using a mass
spectrometer.
• Proton = 1.67x10^-24 g
• Neutron =1.67x10^-24g
• Electron = 9.11x10^-28g (very insignificant)
• Mass # in grams for an atom is important
information but values are not easy to work
with .
Atomic Mass Unit (amu)
• Compare atom’s mass with carbon.
• Ex. If Helium has a mass of 4 amu how does it
compare with Carbons mass in amu?
• Amu = 1/12 C, 4(1/12) = 1/3x mass of C
• Ex. If Sulfur has a mass of 32 amu, how does
it compare with Carbon mass in amu.
• Amu = 1/12 C
32/12 = 2.67x mass of C
Atom Composition
• If we know the atomic mass and the atomic
number we can determine the atom’s
composition : # of e•
# of p+
•
# of n0
Atomic Composition
Shorthand
• Shorthand method of atomic composition:
Carbon-12 has an atomic # of 6
Ex. Oxygen-16 has an atomic # of 8
Ex. Silicon-28 has an atomic # of 14
Periodic Table
• The periodic table is arranged in numerical
order by an atom’s atomic #.
• What is an atom’s atomic #?
• Why are the elements arranged this way?
Atom’s chemical nature is dependent upon its
charged particles :
Atom’s protons remain conserved with most
reactions because present within nucleus.
The # of electrons (electron cloud) will
fluctuate with most reactions
Periodic Table Trends
• Organizing atoms based on atomic #
establishes trends:
• Period= The horizontal rows within a periodic
table. The atoms in each row share a pattern
of properties.
• Group= The vertical columns of the periodic
table. Atoms in each group share similar
physical and chemical properties.
•What is the total # of atoms making up the Kandium sample? Record in table.
Bell Ringer
(9/10/09)
1. How are elements arranged in the periodic table?
2.What does period and group refer to on the
periodic table?
3.Identify which subparticles exist in the nucleus and
the electron cloud.
4.Which two subparticles affect the chemical nature
of atoms?
5.What subparticle determines the mass of the atom?
6.Which subparticle is also the atomic #?
Objectives
• I can determine the atomic composition of atoms when I
know the atomic mass and atomic #.
• I can recognize that the periodic table is organized by an
element’s atomic number.
• I can divide the elements in the periodic table into periods
and groups.
• I can identify and distinguish between metals, nonmetals,
and metalloids on the periodic table.
• I can determine if an atom is neutral or has an overall
charge based on the # of electrons present within the
atom.
Periodic Table Trends
• Organizing atoms based on atomic #
establishes trends:
• Period= The horizontal rows within a periodic
table. The atoms in each row share a pattern
of properties.
• Group= The vertical columns of the periodic
table. Atoms in each group share similar
physical and chemical properties.
Periodic Table
Elements can be classified into 3 groups:
I. Metals= good conductors of electricity and heat.
II.Non-metals= primary make-up of life.
Synthetic (man-made) materials.
Poor conductors of electricity and heat.
III Metalloids = properties of metals and non-metals.
Neutral Atom
• What are the two charged subatomic particles that
make-up an atom?
• Neutral atoms: # protons = # of electrons
• What happens if they are not balanced?
Charged Atom
Atoms become charged when they gain or loose
electrons. This would affect the atom’s balance
between # of p+ and # of e-.
• Charged atoms are called ions.
Ion Types
• Ions = charged atoms
• Two types of Ions
1. Anion= An atom that has gained one or more
electrons.
What charge would an anion have?
• Non-metal ions can be anions.
Ex. What are some examples of anions?
Anions
Ex. Fluorine (F) atomic # = 9
Neutral Fluorine: F
Anion
Ex. Phosphorous (P) atomic # is 15.
Neutral Phosphorous:P
Ion Types
• Cations= An atom that looses one or more
electrons.
What charge would a cation have?
• Metals can be cations.
What are some examples of cations?
Cation
• Ex. Potassium (K) atomic # = 19
• Neutral Potassium: K
Cation
• Ex. Iron (Fe) atomic # = 26
Neutral Iron: Fe
Mass # vs. Atomic Mass
• Mass # = # of protons and # of neutrons in an
atom.
• Atomic Mass = The average mass for an element.
It is determined by taking in account all the isotopes
that make-up an element. You must know the
isotopes relative abundance and mass # to
calculate the atomic mass of the element.
-Atomic mass = observed on the periodic table.
Atoms : To be neutral or charged
• Neutral atom = # p+ is equal to # e• Ions (charged atoms) = change in # of ea. Cation (+ charge) = # of e- is less than in the
neutral atom. Ex. Metals (Na +)
# of e- = subtracting the charge from # of p+
b. Anion = # of e- are more than in the neutral
atom. Ex. Nonmetals. (F-)
# of e- = adding the charge to # of p+
Neutral or Not
1. Beryllium : Be 2+
2. Sulfur: S
3. Sulfur: S 2-
d) the larger the atom the weaker the strong
force is --> larger atoms tend to decay
(nuclear decay)
e) also, atoms with certain numbers of protons
tend to decay--if they have the same number
of protons and neutrons they tend to be more
stable--different numbers--more unstable
5) 4 forces in nature
a) strong force
b) weak force
c) electrical force
d) gravitational force
6) Usages of Nuclear Chemistry
a) production of power
b) killing bacteria in food products
7) Radiation-Radioactivity
a) radiation is electrically charged particles
or waves emitted by an energy source or
decaying atoms.
b) radioactivity - is radiation from an
unstable atom that is splitting or
undergoing decay. There are three types of
radioactive materials
* Alpha radiation - harmful if inhaled or
otherwise enter the body - can be stopped
by clothes, skin or a sheet of paper.
Some producers of alpha particles are
among the longest lasting waves
* beta particles - more penetrating power
than alpha but most serious when inhaled
or ingested -- tend to concentrate in certain
body parts, such as bone -can cause serious
health problems with minimal exposure
* gamma radiation-- highest energy levels similar to x-rays, can penetrate the body
Types of Radiation
• 1. Alpha Radiation : an alpha particle emitted from radioactive
nuclei, consists of 2 protons and 2 neutrons, but no electrons
• Not very harmful
• Large atoms are not very stable and need to decrease mass
• What is the charge and mass of an alpha particle?
• +2 and 4amu
• Example
• 22688Ra → 22286Rn + 42He
•
Radium
Radon
Alpha Particle
Types of Radiation
• Beta Radiation: fast moving electron emitted from a
radioactive element called a Beta Particle.
• Can cause serious health problems especially in bones
• Atoms want to have a 1 : 1 neutron to proton ratio
• Beta emission is used to decrease the neutron to proton ratio.
• What is the charge and mass on a beta particle?
• -1 and 0
• 146C → 147N + 0-1β
Types of Radiation
• Gamma Radiation: Gamma rays are released
from radioactive nuclei.
• Gamma rays have no mass or charge.
• Gamma rays are very harmful and have a very
high energy
* Effects of radioactive particles on biological
systems --can alter cellular function
particularly DNA--carries the cells genetic
code-causing birth defects-can create
mutated forms of cells that can cause
cancerous growths
8) Fusion-Fission
a) fusion uniting of nuclei of two light
elements to form heavier nucleus- example
b) fission - a heavy nuclide splits into two or
more intermediate- sized fragments when hit
in a particular way by a neutron --utilized by
nuclear power plants --to make nuclear bombs
Periodic Table Trends
• Organizing atoms based on atomic #
establishes trends:
• Period= The horizontal rows within a periodic
table. The atoms in each row share a pattern
of properties.
• Group= The vertical columns of the periodic
table. Atoms in each group share similar
physical and chemical properties.
Elements in a Period (row)
• The mass of an atom increases as you go from
left to right across any period.
Metals, Non-metals, and Metalloids
• Metals= shiny, good conductors of electricity and
heat, malleable, and ductile.
(primarily solids)
• Non-metals = poor conductors of electricity,
sometimes transparent, neither malleable nor
ductile, brittle.
(solids, liquids and gases)
Metalloids= Weak conductors of electricity, useful
semi-conductors. They can exhibit metal and
nonmetal properties.
Postulate 4 is actually the Law of
Definite Proportions,
by Joseph Louis Proust in 1797.
a) a given chemical compound always
contains the same proportion by mass of its
constituent elements or...
b) the relative amount of each element in a
particular compound is always the same,
regardless of preparation or source.
Assignment: Illustrate the following Atomic Models
•Dalton’s Atomic Model
•Thomson’s Plum Pudding Model
• Rutherford’s Nuclear Model
• Modern Atomic Model.
Thomson’s Plum Pudding Model