ATOMIC
STRUCTURE
Particles &
Waves
NOTEBOOK PAGES:
12,28-29,66
MATTER’s BUILDING BLOCKS
1. All matter is made up of smaller particles called
atoms, ions, molecules, and macromolecules.
2. Atoms are neutral and have 3 subatomic particles:
PROTON, ELECTRON, and NEUTRON.
3. Ions are made up of a single atom or a group of
atoms that behave as one. All ions have an electrical
charge.
4. Molecules are made up of 2 or more atoms and are
neutral;
5. Macromolecules are like molecules except they are
made up of hundreds of atoms. They are neutral.
MATTER’s BUILDING BLOCKS
Helium Atom
Water Molecule
Sodium Ion
DNA
Macromolecule
Proton, Neutron, and Electron
Relative Masses
proton
The electron is so
light compared to
the neutron and
proton, that it is
givenelectron
a zero for its
atomic mass unit.
The elephant is
only slightly
more massive
than the
rhinoceros.
neutron
And so the
neutron is
slightly more
massive than
the proton.
JJ
Thomson
1897
Niels Bohr
1913
Some Atomic Models
Ernest
Rutherford
1909-1911
Wolfgang Pauli, Erwin Schroedinger, James
Chadwick, Enrico Fermi, Paul Dirac, just to
name a few. 1920-1930’s
Subatomic Particles
SUBATOMIC
PARTICLES
MASS
(kg)
(amu)
LOCATION
in the
ATOM
1.6726231 10-27 kg
PROTON
1 amu
nucleus
CHARGE
+1
1.674928610-27 kg
NEUTRON
1 amu
nucleus
0
Electron
Cloud
-1
9.1093897 10-31 kg
ELECTRON
0 amu
Volume –or- Space
Soccer
Field
Analogy
The ‘Soccer
Field’
Analogy
is not to
be confused with thePea
‘Rhinoceros,
= nucleus
Elephant, & Ant’ analogy which is
used when trying to explain the
differences in mass of the 3
Goal Posts= edge of
the electron cloud
subatomic particles. The ‘Soccer
Field’ Analogy is used when trying
to explain the space the subatomic
particles occupy.
Electrons = shielding + valence electrons
15
31
15
P
= 10 + 5
2
8
5
Shielding Electrons
Valence
Electrons
Electrons= shielding + valence electrons
247
Bk
97
2
8
18
32
27
8
2
Shielding Electrons= 2+8+18+32+27+8= 95
-or-
97-2 = 95
Total Electrons – valence electrons = Shielding e-S
Valence Electrons
The Four Forces of the Universe
Name of Force
Gravity
Holds Together…..
Attractive Force that
hold Massive Bodies
together.
Holds other subatomic
forces together.
Weak Force
Strong Nuclear Force Holds the nucleus
together.
Electromagnetic Force Opposites attract; Like
charges repel each
other.
The Four Forces of the Universe
Name of Force
Gravity
Holds Together…..
Attractive Force that hold Massive
Bodies together.
The Four Forces of the Universe
Name of Force
Holds Together…..
Weak Force
Holds other subatomic
forces together.
The Four Forces of the Universe
Name of Force
Holds Together…..
Strong Nuclear Force Holds the nucleus
together.
The Four Forces of the Universe
Name of Force
Holds Together…..
Electromagnetic Force Opposites attract; Like
charges repel each
other.
THE MODERN ATOMIC MODEL
(a.k.a. Quantum Mechanics model)
THE ATOM CAN BE BROKEN
DOWN INTO 3 SMALLER
PARTICLES:
– PROTON-LOCATED IN
THE NUCLEUS & HAS A
POSITIVE CHARGE.
– NEUTRON-LOCATED IN
THE NUCLEUS & HAS A
NEUTRAL CHARGE.
– ELECTRON- LOCATED
OUTSIDE OF THE
NUCLEUS IN THE
ELECTRON CLOUD &
HAS A NEGATIVE
CHARGE.
The Electron Cloud Model
• Electron Cloud
Model - an atom
consists of a dense
nucleus composed
of protons and
neutrons
surrounded by
electrons that
exist in different
clouds at the
various energy
levels.
• Erwin Schrödinger
and Werner
Heisenburg
developed
probability
functions to
determine the
regions or clouds in
which electrons
would most likely
be found.
(post 1930s)
FLAME TESTS
• What is the flame test?
The flame test is used to visually
determine the identity of an unknown
metal of an ionic salt based on the
characteristic color the salt turns the
flame of a Bunsen burner.
How is the test performed?
1. First, you need a clean wire loop! Place
the loop in a bunsen burner flame for
several seconds.
2. Test the cleanliness of the loop by
inserting it into a bunsen burner flame.
If a burst of color is produced, the
loop was not sufficiently clean. CLEAN
AGAIN IF NECESSARY.
FLAME TESTS- continued
3. The clean loop is dipped in a solution of
an ionic (metal) salt. The loop with the
sample is placed in the clear or blue
part of the flame and the resulting
color is observed.
4. Match the color of the flame with the
Literature Values of Elements & Their
Characteristic Colors of Flames.
ATOMIC MODEL of HYDROGEN
its electron has gained energy and has
moved up a level.
THE ELECTRON FALLS BACK TO
GROUND STATE
LIGHT TRAVELS IN WAVES
CREST
TROUGH
ELECTROMAGNETIC SPECTRUM
LIGHT TRAVELS VIA ELECTROMAGNETIC WAVES
IDENTIFYING LIGHT IN MORE DETAIL
1. THE LIGHT EMITTED FROM AN ELEMENT
THAT IS EXCITED CAN BE IDENTIFIED
MORE PRECISELY BY PASSING IT
THROUGH A PRISM.
2. THE LIGHT SEPARATES INTO THE
DIFFERENT COLORS THAT MAKE IT UP.
3. BECAUSE EACH COLOR OF WHITE LIGHT
HAS A DIFFERENT WAVELENGTH, IT CAN
BE SEPARATED.
What metals do colors indicate?
Color
Metal
Red
Carmine: Lithium compounds. Masked by barium or sodium.
Scarlet or Crimson: Strontium compounds. Masked by
barium.
Yellow-Red: Calcium compounds. Masked by barium.
Yellow
Sodium compounds, even in trace amounts. A yellow flame is not indicative
of sodium unless it persists and is not intensified by addition of 1% NaCl to
the dry compound.
White
White-Green: Zinc
Green
Emerald: Copper compounds, other than halides. Thallium.
Blue-Green: Phosphates, when moistened with H2SO4 or B2O3.
Faint Green: Antimony and NH4 compounds.
Yellow-Green: Barium, molybdenum.
Blue
Violet
Azure: Lead, selenium, bismuth, CuCl2 and other copper compounds moistened with hydrochloric acid.
Light Blue: Arsenic and come of its compounds.
Greenish Blue: CuBr2, antimony
Potassium compounds other than borates, phosphates, and silicates. Masked by sodium or lithium.
Purple-Red: Potassium, rubudium, and/or cesium in the presence of sodium when viewed through a
blue glass.
FLAME TESTS
STRONTIUM
POTASSIUM
BARIUM
CALCIUM
What are the limitations of this test?
1. The value of the flame test is
limited by interference from other
brighter colors and by ambiguities
where certain different metals cause
the same flame color.
2. Sodium, in particular, is present in
most compounds and will color the
flame. Sometimes a colored glass is
used to filter out light from one
metal. Cobalt glass is often used to
filter out the yellow of sodium.
COBALT (Co), as a FILTER
GAS DISCHARGE TUBES
1. THE NEXT LAB WE WILL STUDY THE
EMISSION SPECTRA OF SEVERAL
ELEMENTS. IT IS MORE RELIABLE
THAN SIMPLE FLAME TESTS.
2. THE LINE SPECTRA OF THE
ELEMENTS HELPS IN IDENTIFYING
UNKNOWN ELEMENTS.
3. LINE SPECTRA
EMISSION SPECTRA
1. Different elements emit different
emission spectra when they are excited
because each type of element has a
unique energy shell or energy level
system, WHERE the electrons hang
out.
2. Each element has a different set of
emission colors because they have
different energy level spacing. We will
see the emission spectra or pattern of
wavelengths (atomic spectra) emitted
by EIGHT different elements in this
lab.
THE CONTINUOUS SPECTRUM
Line Spectra
Because only certain energy levels are allowed to atoms,
the light emitted by atoms can only have certain
frequencies (and therefore colors).
This is called a line
spectra.
LINE SPECTRUM for HYDROGEN
700nm
600
500
LINE SPECTRUM for HELIUM
400nm
LAB: Emission Spectra
1. The purpose of this lab is to view the
photons emitted from various elements
when gasses of the elements are
electrified. (Yikes!)
2. The gases of the elements are in spectrum
tubes which are placed in electrical boxes
with a light switch.
3. Turn on the switch and an electrical
current passes through the element.
4. The valence electrons of the element
become ‘excited’ and move up an energy
level in the atom.
LAB: Emission Spectra-continued
5. The electron is unstable in the higher
state and falls back down to the original
energy level, called the ‘ground state’.
6. In the process of falling back down it
releases photons.
7. Photons are packets of light that travel
at specific wavelengths. The emitted light
will be viewed through a spectroscope.
LAB SET-UP
ALL EQUIPMENT IS
FRAGILE and WILL
BREAK EASILY,
HANDLE WITH CARE
and MOVE SLOWLY
DURING THE LAB!!!
BLUE
SPECTROSCOPE
POWER SUPPLY with
the GAS DISCHARGE
TUBE
BLACK
SPECTROSCOPE
What do all the colored lines mean?
1. The colored lines represent the photons of
light that travel at specific wavelengths.
2. Purple light is composed of photons with
wavelengths from 400nm to 455nm.
3. Blue light is composed of photons with
wavelengths from 450nm to 505nm.
4. Green light is composed of photons with
wavelengths from 495nm to 570nm.
5. Yellow light is composed of photons with
wavelengths from 580nm to 600nm.
6. Red light is composed of photons with
wavelengths from 600nm to 730nm.
Light has 2 Natures
The Particle Nature……
….and the WAVE Nature.
The Packet of Light is called the Photon
Calculating the Energy of a Photon
E = hc

E = energy

= The Greek letter ‘lambda’ which is the symbol for
wavelength
h= Planck’s Constant which is 6.64 x 10-34 Js
c = The speed of light which is 3.00 x 108 m/s
Sample Problem A
Calculate the energy of a BLUE line
that has a wavelength () of 490 nm.
E = hc

h= Planck’s Constant which is 6.64 x 10-34 J  s
c = The speed of light which is 3.00 x 108 m/s
WARNING: Don’t mix apples
and oranges
1. The speed of light
is 3.00 x 108 m/s.
2. What is the unit of
length in this
measurement?
3. ‘meter’
4. In what unit of length
is the wavelength?
5. ‘nm’ which stands for
nanometer. You must
change nm to meter
before you can do the
final calculation.
So…..change nm to meters. The conversion factor is
1 meter = 109 nanometers
490 nm x 1 meter =
109 nm
490 x 10-9 m
Fill in the variables with the correct quantity……
E = hc

E= (6.64 x 10-34 J  s )(3.00 x 108 m/s)
490 x 10-9 m
Re-Group the coefficients and
the powers of 10
(6.64 x 3.00 ) x (10-34 x 108)
490
x
10-9
Move the exponent from the
denominator to the numerator…
(6.64 x 3.00 ) x (10-34 x 108)
490
x
10-9
Cancel the units that you
can….
E= (6.64 x 10-34 J  s )(3.00 x 108
m / s)
490 x 10-9 m
The only unit left is the
Joule (J), which is the
correct unit for Energy.
Don’t forget to change the sign on the exponent
when you move it from one place to another…..
(6.64 x 3.00 ) x (10-34 x 108 x 109 ) = 0.0407 x 10-17J
490
x
10-9
CORRECT NOTATION BECAUSE 4.07
IS A NUMBER BETWEEN 1 AND 10!!!
4.07 x 10-19J
HANDLING THE EXPONENTS:
ADD -34 + 8 + 9 = -17
0.0407X 10-17 IS NOT PROPER SCIENTIFIC
NOTATION SO MOVE THE DECIMAL POINT
TO THE RIGHT 2 PLACES TO THE RIGHT AND
DECREASE -17 BY 2
Sample Problem B
Calculate the energy of a RED line that
has a wavelength () of 610 nm.
E = hc

h= Planck’s Constant which is 6.64 x 10-34 J  s
c = The speed of light which is 3.00 x 108 m/s
So…..change nm to meters. The conversion factor is
1 meter = 109 nanometers
610 nm x 1 meter =
109 nm
610 x 10-9 m
Fill in the variables with the correct quantity……
E = hc

E= (6.64 x 10-34 J  s )(3.00 x 108 m/s)
610 x 10-9 m
Cancel the units that you
can….
E= (6.64 x 10-34 J  s )(3.00 x 108
610 x 10-9 m
m / s)
Re-Group the coefficients and
the powers of 10
(6.64 x 3.00 ) x (10-34 x 108)
610
x
10-9
Move the exponent from the
denominator to the numerator…
(6.64 x 3.00 ) x (10-34 x 108)
610
x
10-9
Cancel the units that you
can….
E= (6.64 x 10-34 J  s )(3.00 x 108
m / s)
610 x 10-9 m
The only unit left is the
Joule (J), which is the
correct unit for Energy.
Don’t forget to change the sign on the exponent
when you move it from one place to another…..
(6.64 x 3.00 ) x (10-34 x 108 x 109 ) = 0.0407 x 10-17J
610
x
10-9
CORRECT NOTATION BECAUSE 4.07
IS A NUMBER BETWEEN 1 AND 10!!!
3.27 x 10-19J
HANDLING THE EXPONENTS:
ADD -34 + 8 + 9 = -17
0.0407X 10-17 IS NOT PROPER SCIENTIFIC
NOTATION SO MOVE THE DECIMAL POINT
TO THE RIGHT 2 PLACES TO THE RIGHT AND
DECREASE -17 BY 2