Brief Instructions
An electron configuration is a method of indicating the arrangement of electrons about a nucleus. A typical
electron configuration consists of numbers, letters and superscripts with the following format:
1. A number indicates the energy level ( The number called the principal quantum number.)
2. A letter indicates the type of orbital; s, p, d, f.
3. A superscript indicates the number of electrons in the orbital. Example 1s2 means that there are two
electrons n the “s” orbital of the first energy level. The element is helium.
To write an electron configuration:
1. Determine the total number of electrons to be represented.
2. Use the Aufbau process to fill the orbitals with electrons. The Aufbau process requires that electrons
fill the lowest energy orbitals first. In another words, atoms ae built from the ground upwards.
3. The sum of the superscripts should equal the total number of electrons.
Example: Mg (12 electrons) – 1s2 2s2 2p6 3s2
Configuration Writing Practice:
Write a ground state electron configuration for each neutral atom. Ground state means that all of the
lowest possible energy levels (up to the proper number of electrons for the element) are filled.
1. Na
2. Pb
3. Sr
4. U
5. N
6. Ag
7. Ti
8. Ce
9. Cl
10. Hg
If each orbital can hold a maximum of two electrons, how many electrons can each of the following hold?
2s orbitals _______
5p orbitals _______
4f orbitals ________
3d orbitals ________
How many S orbitals can there be in an energy level? _________
How many electrons can occupy an s orbital? ________
How many p orbitals can there be in an energy level? _______
Which is the lowest energy level that can have a s orbital? ________
Which is the lowest energy level that can have a p orbital? ________
How many d orbitals can there be in an energy level? ________
How many d electrons can there be in an energy level? ________
Which is the lowest energy level having d orbitals? _________
4d orbitals ________
How many f electrons can there be in an energy level? ________
Which is the lowest energy level having f orbitals? _________
How many f orbitals can there be in an energy level? ________
How many energy levels are partially of fully occupied in a neutral atom of calcium? _____________
Which sublevels of the 3rd energy level are filled?
a. in the element argon______________________________
b. in the element krypton. __________________________
For the following elements list the complete electron configuration.
1. Oxygen
2. Cesium
3. Krypton
4. Titanium
5. Scandium
6. Nitrogen
7. Chlorine
8. Fluorine
9. Copper
10. Mercury
For the following elements list the shorthand (noble gas) electron configuration.
1. Boron
2. Cadmium
3. Phosphorus
4. Neon
5. Radon
6. Iodine
7. Iron
8. Bromine
9. Strontium
10. Nickel
Write a ground state electron configuration for these ions. Remember that ions have a change in the total
number of electrons (positive ions have lost electrons and negative ions have gained electrons).
1. O22. Fe2+
3. B3+
4. Ni2+
5. K+
Define:

Crest –

Wave –

Amplitude -

Wavelength -
What is the electromagnetic spectrum?
-
For each of the following wavelengths of visible light, determine the frequency and identify the region
(color) of the electromagnetic spectrum to which it belongs. (The velocity(speed) of light is 3.00 x 108 m/s)
𝒄
𝛎=
𝛌
a. 2.0 x 10 -14 m
b. 4.0 x 10 -9 m
c. 6.0 x 10 -7
d. 1.00 m
For each of the following frequencies of visible light, determine the wavelength, and identify the color of
𝒄
light associated with each frequency. 𝛌 =
𝛎
a. 2.0 x 10 -14 m
b. 4.0 x 10 -9 m
c. 6.0 x 10 -7
d. 1.00 m
A Chemist is using radiation with a wavelength of 6 x 10-9m.
a. What is the frequency of this radiation in Hz?
b. Identify this radiation as red, blue, infrared, ultraviolet, and so on.
c. Calculate the energy in J for one photon of this radiation. Plank’s constant (h) is 6.626 x 10-34 J
*s𝐸 = ℎ 𝛎
Writing Electron and Orbital Configurations and Electron Dot structures
1. Selenium (Example)
Symbol
Atomic #
Total number of e-
# of Valence e-
Se
34
34
6 (4s2 4p4)
Complete Electron Configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4
Abbreviated (Noble Gas) Electron Configuration
[Ar] 4s2 3d10 4p4
Orbital Configuration
1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6


  

  

    
  
2. Chlorine
Element
Atomic #
Total number of e-
# of Valence e-
Total number of e-
# of Valence e-
Complete Electron Configuration
Abbreviated (Noble Gas) Electron Configuration
Orbital Configuration
3. Calcium
Element
Atomic #
Complete Electron Configuration
Abbreviated (Noble Gas) Electron Configuration
Orbital Configuration
4. Nitrogen
Element
Atomic #
Total number of e-
# of Valence e-
Total number of e-
# of Valence e-
Total number of e-
# of Valence e-
Complete Electron Configuration
Abbreviated (Noble Gas) Electron Configuration
Orbital Configuration
5. Krypton
Element
Atomic #
Complete Electron Configuration
Abbreviated (Noble Gas) Electron Configuration
Orbital Configuration
6. Sodium
Element
Atomic #
Complete Electron Configuration
Abbreviated (Noble Gas) Electron Configuration
Orbital Configuration