Name________________________________Date______________________
Period____________
Electron Review
1. Place the following models in order from earliest thoughts to current thoughts:
Quantum Mechanical, Plum Pudding, Bohr, Planetary
1st:__Plum Pudding___ 2nd:____Planetary____ 3rd: ____Bohr______
4th:__Quantum______
In each box, draw what an atom of sodium looks like under each of the above models
2. Describe the gold foil experiment and how it changed our understanding of the location of the
electron. How is this different from the current model?
The gold foil experiment was an experiment conducted by Ernest Rutherford in which alpha particles
(positive) were shot at a thin piece of gold foil. The scientists expected the particles to bounce off the
foil and return (because of the positive charge assumed for most of the atom under the existing plum
pudding model). Instead, most went straight through showing the atom is mostly empty space. Some
returned as expected showing that there is positive charge in the atom but that is concentrated in small,
dense pockets called a “nucleus”. Lastly, some were deflected at odd angles proving that there were
small negative particles outside the nucleus (electrons).
Before, scientists believed that the atom was a sea of protons with electrons floating in the sea at
random. After the experiment, scientists believed that the atom contains a nucleus that stores all the
protons and the electrons rotated outside the nucleus.
3. The model of the atom was revised from the planetary to the Bohr model because of what
discovery? Explain what was happening in this discovery and how it led to the inclusion of
energy levels in the atom.
The discovery of energy levels- different elements have electrons in different energy levels
which we know because they give off different colors (energies) of light when excited. For
example when a metal like Lithium is heated, its electron gets excited and jumps to a higher
energy level. Then, the electron returns to its original position (ground state) and this energy is
released as light.
4. The most modern representation of the atom is the quantum mechanical model. Explain the
difference between this model and the Bohr model.
The Bohr model states that there is a nucleus with protons and neutrons in the center of the
atom and that electrons can be found in specific energy levels that are evenly spaced from the
nucleus. The quantum mechanical model agrees with the structure and placement of the
nucleus and that the electrons can be found in energy levels outside the nucleus but found that
electrons move at the speed of light. Because they move so quickly, they cannot be pinpointed
at any given time. Therefore, their location is represented in terms of probability. The clouds (s,
p, d, and f) represent separate clouds within the larger energy levels (1-7) and are not evenly
spaced from the nucleus.
Name________________________________Date______________________
Period____________
Electron Review
5. Draw a wave and label the amplitude, wavelength, and find its frequency.
If this passed in 1 second, the frequency would be 2.
6. Consider the following types of waves: visible light, ultraviolet light, x-ray, radio, and micro.
a. Arrange them in order of decreasing wavelength.
Radio, micro, visible, ultraviolet, x-ray
b. Arrange them in order of decreasing frequency.
X-ray, ultraviolet, visible, micro, radio
7. Calculate the wavelength of the electromagnetic radiation whose frequency is 7.5 x 1012 Hz.
4 x 10-5 m
8. Determine the frequency of light with a wavelength of 4.2 x 10-7 cm. (Watch your units!)
7.14 x 1016 Hz
9. Determine the energy (in joules) of a photon whose frequency is 3.55 x 1017 Hz.
2.35 x 10-16 J
10. What is the frequency of a radio wave with an energy of 1.55 x 10-24 J/photon?
2.34 x 109 Hz
11. Cobalt-60 is an artificial radioisotope that is produced in a nuclear reactor for use as a gammaray source in the treatment of certain types of cancer. If the wavelength of the gamma radiation
from a cobalt-60 source is 1.00 x 10-3 nm, determine its energy in joules/photon.
1.99 x 10-13 J
12. Write the ground state electron configuration for each atom:
Na
__1s22s22p63s1____________________________
Pb
_1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p2________
Sr
_1s22s22p63s23p64s23d104p65s2________________
U
_1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f4__
N
_1s22s22p3_______________________________
13. How many electrons can each of the following hold?
a. 2s
____2______
b. 5p
____6______
c. 4f
____14______
d. 3d
____10______
e. 4d
____10______
Name________________________________Date______________________
Period____________
Electron Review
14. Draw the orbital diagrams for each of the elements below:
a. Mn
1s22s22p63s23p64s23d5
b. Ca
1s22s22p63s23p64s2
c. P
1s22s22p63s23p3
d. Se
1s22s22p63s23p64s23d104p4
15. Write the noble gas shorthand for the electron configuration of
a. Y___[Kr]5s24d1_________________________________
i. How many electrons are in each energy level?
st
1 ___2__ 2nd __8___ 3rd __18___ 4th __9___ 5th ___2__ 6th ___0__ 7th ___0__
b. K___[Ar]4s1____________________________________
i. How many electrons are in each energy level?
1st __2___ 2nd __8___ 3rd __8___ 4th __1___ 5th _____ 6th _____ 7th _____
c. Br___[Ar]4s23d104p5____________________________
i. How many electrons are in each energy level?
st
1 __2___ 2nd __8___ 3rd __18___ 4th __7___ 5th _____ 6th _____ 7th _____
16. Which of the rules do each of the following electron energy diagrams violate?
a)
b)
c)
a. Hunds Rule- electrons fill all empty orbitals in an energy level before pairing
b. Aufbau-electrons fill lower energy levels completely before moving up
c. Pauli Exclusion- electrons in the same orbital must have opposite spins