02 - Electrons in atoms

Ionisation Energy

The energy needed to remove 1 mole of electrons from 1 mole of atoms of an element in gaseous state to form 1 mole of gaseous ions.

First Ionisation Energy (IE1)

The energy requires to remove the first electron from 1 mole of electrons from 1 mole of atoms of an element in a gaseous state to form 1 mole of +1 gaseous ions.

Successive ionisation energies

The energy required to remove a sequence of electrons from an atom.

Factors that influence ionisation energy

• Nuclear charge

• Distance of outer electrons from nucleus (atomic radius)

• Shielding effect

• Spin-pair repulsion between electrons

Sub-shells

Regions of principal quantum shells where electrons exist in defined areas associated with particular amounts of energy

The four main sub-shells

S P D F

Atomic orbitals

Regions of space outside the nucleus that can be occupied by a maximum of 2 electrons.

Number of orbitals in S

1

Number of orbitals in P

3

Number of orbitals in d

5

Shape of S-orbital

Spherical

Shape of P-orbital

Dumbell

Spin pair repulsion

A pair of electrons in the same orbital that repel each other. They spin in the opposite direction to reduce repulsions.

Free radical

A species with one or more unpaired electron

Covalent atomic radius

Covalent atomic radius is half the distance between the nuclei of two covalently bonded atoms of the same type.