Question

3. a) Explain the reason for the variation of the first ionization energies of the third period elements

Answer 1

Ionization energy is the amount of energy required to remove an electron from neutral gaseous electrons . Across period, in a periodic table from left to right I.E should increase.  Third period elements are : Na, Mg, Al, Si, P, S , Cl, Ar Order of I.E in third period: Na<Mg >Al<Si<P<S<Cl <Ar In third period element with highest ionization energy is argon due to stable octet configuration . Case 1: Mg has more I.E than Al. Mg>Al  due too its stable ns2 configuration of Mg. Case 2: P has more I.E than sulphur (S) a because phosphorous has half filled p sub shell in its valence shell that gives extra stability and hence more energy is required to remove the electron.