WHAT IS IONISATION ENERGY?
Ionisation Energy is a measure of the amount
of energy needed to remove electrons from atoms.
As electrons are negatively charged and protons in the nucleus are positively charged, there will be an attraction between them. The greater the pull of the nucleus, the harder it will be to pull an electron away from an atom.
FIRST IONISATION ENERGY - Definition
The energy required to remove ONE MOLE of electrons from each atom in ONE MOLE of gaseous atoms to form ONE MOLE of gaseous positive ions.
e.g. Na(g) Na+(g) + e-
Al(g) Al+(g) + e-
Make sure you write in the (g)