Chemistry: 1.1 Atomic Structure Part 2

S, p, d, f

2

8

18

32

Orbitals

A region which can hold a maximum of two electrons with opposite spins

1 (holds a max of 2 electrons)

3 (holds a max of 6 electrons)

5 (holds a max of 10 electrons)

7 (holds a max of 14 electrons)

An up arrow

An up arrow to the left of a down arrow

Shielding from the nucleus

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

So that electrons remain unpaired if possible

The electrons pair up

It’s closest to the nucleons

1s2 2s2 2p3

1s2 2s2 2p6 3s2 3p6 4s1

With half full + full 3D shells (3D fills before 4s)

By using the symbol of the previous noble gas

4s

Energy needed to remove one electron from each atom in one mole of gaseous atoms

1. Atomic radius- distance from nucleus to outer electron

2. Nuclear charge (no of protons)

3. Shells- more shells leads to more shielding

The smaller the ionisation energy, the easier it is to remove outer electron

It decreases down a group

• shells increase so shielding increases

• atomic radius increases to outweigh increase in nuclear charge

• nuclear attraction on outer electron decreases so 1st ionisation energy decreases

Increase in 1st ionisation energy across a period

• shells + shielding remain same

• nuclear charge increases

• atomic radius decreases

• nuclear attraction on outer electron increases so first ionisation energy increases

• borons outer electron in 2p sub shell- further away from nucleus

• easier to remove

*easier to remove as electrons are now paired- inter-orbital repulsion

• more shells - more shielding

• nuclear attraction decreases

• ionisation energy lower

Electrons become harder to remove

1: mg(g) > mg+(g) + e-
2: mg+(g)> mg2+(g) + e-
3: mg2+(g) > mg3+(g) + e-
4: mg3+(g) > mg4+(g) + e-

Altogether: mg4+(g) + 4e-

As electrons are removed, fewer electrons are being attracted by the same number of protons. Therefore, attraction sequentially increases as successive ionisation energies increase

The number of electrons in each energy level, and provides evidence for the existence of energy levels

The electrons are being removed from the same shell

The electrons are being removed from different shells

Magnesium has more protons

| Attraction between nucleus and outer electron is higher

Neons outer electron is closer to the nucleus than sodiums

| Less shielding and stronger attraction between nucleus and outer electron

Electron is being removed from 2p sub shell which is further from nucleus than 2s