Why do Non-metals have high Ionization energy values?

Ionization Energy: The amount of energy required to remove an electron from a gaseous atom is known as ionization energy.

• The size of non-metals is small as compared to metals due to which electrons are more tightly held in non-metals.
• Non-Metals are electronegative elements and tend to share or accept electrons in a chemical reaction.
• Due to the electrons accepting nature of non-metals, they gains more electrons to complete their octet.
• So, non-metals have high ionization enthalpy due to their small size and high electronegativity as compared to metal.