Chemistry 2.2.2: Sub-Shells + Energy Levels

Question 1

what are the rules for filling orbitals?

Answer 1

• fill the lowest energy first
• fill orbitals singularly before doubling
• electrons must have opposite spins

Question 2

what are the sub-shells?

Answer 2

S, P, D, F

Question 3

how many electrons are held in each shell (first 4)?

Answer 3

n = 1, 2 electrons
n = 2, 8 electrons
n = 3, 18 electrons
n = 4, 32 electrons

Question 4

increasing order of sub-shells:

Answer 4

4f
4d
4p
3d
4s
3p
3s
2p
2s
1s

Question 5

definition of atomic orbitals:

Answer 5

a region around the nucleus that can hold up to two electrons, with opposite spins.

Question 6

definition of electronic configuration:

Answer 6

the arrangement of electrons in an atom or ion.

Question 7

what are the rules of electron configuration (Aufbau principle)?

Answer 7

• electrons are added singularly before doubled
• lowest available energy level is filled first (the one closest to the nucleus)
• each energy level must be full before the next higher energy level fills

Question 8

why is 4s filled before 3d?

Answer 8

this is due to 4s orbital having a slightly lower energy level than 3d orbital.