Question

Define ionisation energy.how do ionisation energy very across a period and down a group?​

Answer 1

Answer:

Ionization energy refers to the amount of energy needed to remove an electron from an atom. Ionization energy decreases as we go down a group. Ionization energy increases from left to right across the periodic table.

Answer 2

Answer:

Ionization energy, also called ionization potential, in chemistry and physics, the amount of energy required to remove an electron from an isolated atom or molecule. ... Among the chemical elements of any period, removal of an electron is hardest for the noble gases and easiest for the alkali metals.

Explanation:

Hope it helps