Question

Why does the ionization energy of elements increase from left to right in a period?

Answer 1

Ionization energy: Negatively charged electrons in an atom are attracted by the positively charged nucleus. For removing an electron this attractive force must be overcome by spending some energy.

The minimum amount of energy required to remove an electron from a gaseous atom in its ground state to form a gaseous ion is called ionization energy. It is measured in units of ${\mathrm{kJmol}}^{-1}$

Variation of ionization Energy in a Period:

• As we move from left to right in a period, electrons are added to the same shell.
• As the number of electrons and protons goes on increasing the attraction goes on increasing and atomic size decreases.
• Thus the outermost shell electrons come closer to the nucleus and are more firmly bound.
• Thus, more amount of energy is required to remove an electron from the outermost shell, and hence, Ionisation Potential increases.