Download Worksheet – Quantum Numbers

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Orbital Diagrams and Quantum Numbers
Modified from www.gcisd-k12.org/cms/lib/TX01000829/.../quantum%20numbers.doc and kentchemistry.com
Aufbau Principle - electrons fill orbitals starting at the lowest available energy state before filling higher states (1s before 2s).
Pauli Exclusion Principle - An orbital can hold 0, 1, or 2 electrons only, and if there are two electrons in the orbital, they must have
opposite (paired) spins. When we draw electrons, we use up and down arrows. So, if an electron is paired up in a box, one arrow is
up and the second must be down. Therefore, no two electrons in the same atom can have the same set of four Quantum Numbers.
incorrect; electrons must spin in opposite directions
correct; the electrons have opposite spins
Hund’s Rule - When filling sublevels other than s, electrons are placed in individual orbitals before they are paired up. Electrons fill
like people do on a bus. You would never sit right next to someone you did not know if there are free seats available, unless of
course all the seats are taken then you must pair up.
Orbital Diagram Questions:
1. Which electron configuration represents a violation of the Pauli Exclusion Principle?
A)
B)
C)
D)
2. Which electron configuration represents a violation of Hund's rule for an atom in its ground state?
A)
B)
C)
D)
3. The correct order of increasing energy of atomic orbitals is?
A) 5p<4f<6s<5d
B) 5p<6s<4f<5d
C) 4f<5p<5d<6s
D) 5p<5d<4f<6s
4. The orbital diagram in which both Pauli’s Exclusion Principle and Hund’s rule are violated (2s and 2p orbitals shown):
5. Electrons would first enter into which orbital?
A) 5s
B) 3s
C) 3p
D) 4f
6. Which one of the following is the correct electron configuration for a ground-state nitrogen atom?
A)
B)
C)
D)
Quantum Numbers
This is our final way to describe the location of an electron. It consists of four numbers that act as coordinates
to locate the electron’s position. These numbers will refer only to the element’s highest energy electron
because the others fall into the same locations that have been described in the elements preceding it.
1. Principle Quantum Number (n) is ENERGY LEVEL (SHELL).
O Indicates distance from the nucleus
a. How do you determine n?
b. Possible values of n?
2. Second Quantum Number (ℓ) is the electron SUBSHELL
a. Indicates the shape of the region.
i. Spherical - ______
ii. Dumbbell - ______
iii. Double dumbbell donut - ______
iv. “Fancy” - ______
b. How do you determine ℓ ?
c. Possible values of ℓ ?
3. Magnetic Quantum Number (mℓ) is the electron ORBITAL
a. Indicates the orientation of the region in space
b. How do you determine mℓ ?
c. Possible values of mℓ ?
4. Spin Quantum Number (ms):
a. When two electrons are in a magnetic field, they will align opposite of one another (same as the
up and down arrows). This is called the “spin”.
b. The electrons within an orbital must have opposite spins to overcome their repulsion.
c. How do you determine ms ?
d. Possible values of ms ?
Quantum Numbers Practice Problems
Fill in the orbital notation (arrows) below, then write the four quantum numbers which describe the location of
the highest energy (last) electron of the following elements:
Element 1s
1. Al
2. Ne
3. P
4. Fe
5. Mg
6. Be
2s
2p
3s
3p
4s
3d
Quantum Numbers
Give the four quantum numbers which describe the location of each of the following:
7. The 4th electron in carbon_____________________________________________
8. The 25th electron in Mn_______________________________________________
9. The 57th electron in Ho_______________________________________________
10. The 49th electron in Xe______________________________________________
Identify the element whose highest energy electron would have the following four quantum numbers:
11. 3, 1, -1, +1/2___________________________________________________
12. 4, 2, +1, +1/2___________________________________________________
13. 6, 1, 0, -1/2____________________________________________________
14. 4, 3, +3, -1/2___________________________________________________
15. 2, 1, +1, -1/2___________________________________________________
Which of the following represents a permissible set of quantum numbers? (answer “yes” if permissible and
“no” if no permissible). If no, state why the set won’t work.
16. 2, 2, +1, -1/2___________________________________________________
17. 5, 1, 0, +1/2____________________________________________________
18. 6, 3,-2, +1/2____________________________________________________
19. 7, 0, 0, -1/2____________________________________________________
20. 4, 1, 8, +1/2____________________________________________________