Define ionization energy.Explain on which the ionization energy depends on .

Explanation

Ionization enery : the Energy requied to remove an electron from the outermost orbit. Ionization energy of an element depents on its :
1) Nuclear charge : More the nuclear charge : More the nuclear charge , more is the ionization energy .
Ex : Between `""_(11) Na and ""_(17) Cl ` chlorine atom has more ionization energy .
2) Screening effect or shielding effect : The shells with electrons between nucleus and the valance shell . act as screens and decrease nuclear attraction over valance electron . this is called the screening effect . More the effect , less is the ionization energy Ex : Between `""_(3) Li and ""_(55) Cs.` the element `""_(55) Cs ` with more inner shells has less ionization energy .
3) Penetration power of the orbitals : Orbitals Belonging to the same main shell main shell have different piercing power towards the nucleus .
Ex : 4S gt 4p gt 4d gt 4f gt in the penetration .
It is easier to get 4f electron than 4s .
Between `""_(4 ) Be (1s ^(2 ) 2S^(2) ) ` and `""_(5 ) B (1s^(2) 2s ^(2) 2p ^(1) ) ` the element `""_(5) B ` has less ionization energy due to lose penetration power of 2p compared to 2s .
4) Stable cconfiguration : It is easier to remove one electron `""_(8 ) O (1s ^(2) 2s ^(2) 2 P ^(4) )` then `""_(7) N (1s ^(2) 2s^(2) 2p ^(3)) . ` this is because `""_(7 ) N ` has stable half filled configuration .
5) Atomic radius : As atomic radius increases , the ionization energy decreases .
Ex : I.E of F is greater than that of I because the atomic radius of I is more than F .