2.2.1 - Electron Structure

Question 1

Electron Configuration

Answer 1

• Electrons orbit around the neucleus in shells
• The closer to the neucleus a shell is, the lower its energy is
• Each shell is divided into sub shells
  S: 2 electrons, spherical shape
  P: 6 electrons, dumbell shape
  D: 10 electrons
  F: 12 electrons
• And each sub shell is divided into orbitals
• When atoms lose electrons, they usually lose them from the outermost shell first
• Unless the outermost electrons are in the D subshell, in which case they lose from the S subshell first

Question 2

Orbitals

Answer 2

• Each subshell is made up of orbitals
• Each orbital can hold a maximum of 2 electrons
• So each sub shell has half the number of orbitals as it does maximum electrons
• Orbitals fill up across the subshell first, with one electron in each subshell, before the second slot in each orbital is filled

Question 3

First Ionisation Energy

Answer 3

• The minimum armount of energy required to remove one mole of electrons from one mole of a gaseous atom

Question 4

Trends in ionisation energy

Answer 4

Down a group:
- Atomic radius increases as there are more shells
- Sheilding increases as there are more inner shells
- So nuclear attraction on outer electrons decreases
- So first ionisation energy decreases (As the attractive force is less)

Across a period:
- Atomic radius decreases as the charge on the nucleus increases as there are more protons in there
- Sheilding stays the same as the number of shells stays the same
- Neuclear charge increases as there are more protons
- So nuclear attraction increases
- So first ionisation energy increases (as the attractive force to the neuclus is greater)

Question 5

Anomalies in ionisation energy across a period

Answer 5

• Ionisation energy overall increases across a period because the attractive force to the nucleus increases as it gains more protons
• However, this dips twice

1st:
- Between the last element in the S subshell and the first in the P subshell
- Since the P ubshell has a higher energy than the S subshell
- There is less nuclear attraction on the p1 electron than there was on the s2 electron
- Therefore it requires less energy to be removed

2nd:
- Between the p3 and p4 electrons
- This is because the electrons start to double up in the orbitals
- So have extra repulsion pushing them from the nucleus
- So require less energy to be removed

Question 6

Successive ionisation energies

Answer 6

• Successive electrons being moved from the same atom
• Ionisation energy increases as more electrons are removed
• This is because as the ratio of protons:eletrons increases, the nuclear attraction on the next electron increases, so it requires more energy to be removed
• There are large increases in the amount of energy required between shells, as shells further down have less energy and greater attraction, so need more energy to be removed