Topic 2 - Atomic structure and periodic table

Why does ionisation energy increase across a period?

• The nuclear charge increases, so force of attraction increases

• The electrons are removed from the same quantum shell

• They experience the same shielding from electrons

What is the electronic configuration of an atom of an element?

The distribution of elements among atomic orbitals

What is the definition of first ionisation energy?

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

What is the definition of second ionisation energy?

The energy needed to remove one electron from each +1 cation in one mole of gaseous cations

Explain why the first ionisation energy of aluminium is less than that of magnesium

The first electron is removed from a 3p subshell is aluminium and a 3s subshell in magnesium

P electrons are sheilded by the s electrons, so the p energy level is higher than s energy level