Electron Configuration - Unit 2

Question 1

In orbital theory, what do s, p, d, and f indicate?
How are these values determined?

Answer 1

The letters s, p, d, f symbolize the subshells in which an electron can exist.
The value of the quantum number l determines the subshell. s, p, d, and f subshells correspond to l = 0, 1, 2, and 3, respectively.

Question 2

What is the value of l for any electron in an s orbital?

Answer 2

For any s electron, l = 0.

l can range from any value from 0 to n-1, and determines the subshell. By definition, if l = 0 for an electron, that electron exists in an s orbital.

Question 3

What is the maximum number of electrons found in an orbital?

Answer 3

Each orbital can hold up to 2 electrons.

Note: When one orbital hold two electrons simultaneously, one must be spin-up and the other spin-down.

Question 4

With 5 orbitals, how many electrons can a d subshell hold?

Answer 4

A d subshell holds up to 10 electrons.

Each of the 5 orbitals can have 1 spin-up electron and 1 spin-down, for a total of 2(5)=10 total.

Question 5

How many electrons can be found in the following subshells?

s subshells
p subshells
d subshells
f subshells

Answer 5

An s subshell holds 1x2=2 electrons
A p subshell holds 3x2=6 electrons
A d subshell holds 5x2=10 electrons
An f subshell holds 7x2=14 electrons

Question 6

The total order of all relevant subshells in the full Periodic Table is:

Answer 6

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d

Question 7

Define Hund’s Rule

Answer 7

Hund’s Rules describe the order of adding electrons to an unfilled subshell.

Hund’s Rules explain that when electrons are added to a subshell that has more than 1 orbital (p, d, or f), each orbital first receives a single electron, each spin-up, until each orbital in the subshell has one electron contained within it.
Only once the orbital is half full will spin-down electrons be added, one per orbital, until the subshell is completely filled.

Question 8

What types of electronic configurations lead to particularly stable atoms?

Answer 8

Fully-filled and half-filled subshells make atoms particularly stable.

In particular, atoms with p3, p6, d5, and d10 valence shell configurations are especially stable.
A classic question will ask about exceptions to typical stability trends, and the answer will be due to an atom having a half-filled subshell.