Electron Structure

Question 1

What is an atomic orbital?

Answer 1

A REGION (NOT PLACE) within an atom that can hold up to 2 electrons with opposite spins.

Question 2

Label the energy levels/shells, and the sub-shells.
State which sub-shells each shell contains.

Answer 2

Shells: 1, 2, 3, 4…
Sub-shells: s, p, d, f…
1: s.
2: s, p.
3: s, p, d.
4: s, p, d, f.

Question 3

State the order of increasing energy.

Answer 3

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 …

Question 4

Energy levels/shells are split into… and…

Answer 4

Shells are split into sub-shells/sub-levels, and sub-shells are split into ORBITALS (which can hold max 2 e-).

Question 5

How are s-orbitals and p-orbitals shaped?

Answer 5

S = sphere
P = dumb-bell

Question 6

What is the max number of electrons each sub-shell can hold?

Answer 6

An orbital can hold max 2 electrons.
S has 1 orbital so can hold max 2.
P has 3 orbitals so can hold max 6.
D has 5 orbitals so can hold max 10.
F has 7 orbitals so can hold max 14.

Question 7

In terms of stability, compare orbitals closer vs. further from the nucleus.

Answer 7

Orbitals closer to the nucleus are more stable and have less energy. Those further are less stable with higher energy.

Question 8

How can we work out the short-hand noble gas electronic configuration?

Answer 8

1. Write out the config. of the element.
2. Find the noble gas closest to this element backwards and write its config.
3. Write the symbol of the noble gas in square brackets, then write whatever is left over/different when you compare these configs.

Question 9

What are the 2 exceptions in electronic configuration? Explain.

Answer 9

Chromium (Cr):
- Expected config: 1s2 2s2 2p6 3s2 3p6 4s2 3d4
Actual config: 1s2 2s2 2p6 3s2 3p6 !4s1 3d5!

Copper (Cu):
- Expected config: 1s2 2s2 2p6 3s2 3p6 4s2 3d9
Actual config: 1s2 2s2 2p6 3s2 3p6 !4s1 3d10!

This is as a half-filled or full d sub-shell is more stable.