IONIZATION ENERGY

IONIZATION ENERGY:

•Definition:

"The first ionization energy is  the energy required to remove the most loosely held electron from 1 mole of gaseous atoms to produce 1 mole of gaseous ions(+1).

   A(g)----------> A+(g) + 1e

•FACTORS AFFECTING IONIZATION ENERGY:

The first ionization energy depends upon following factors;

1. Atomic size is inversely proportional to ionization energy.

2. Nuclear charge is also inversely proportional to ionization energy.

3. Shielding/screening effect: It is also inversely proportional to ionization energy.

4. Nature of orbital: It is difficult to remove electron from s orbital then p orbital .The order for ionization energy in different orbital is;

   s>p>d>f

TRENDS:

Along the period:

•Generally, the ionization energy of the elements increases from left to right in periodic table due to successive increase in the nuclear Charge and decrease in atomic size.

•However, some irregular trends in period 3 are present.e.g. ionization energy of Mg and P are higher than those of Al and S respectively.

Along the group:

Generally, the ionization energy of the elements decrease down the group in periodic table due to successive increase in the no of shells and increase  in atomic size.