Question

although the size of sulphur is smaller than phosphorus but first ionisation enthalpy of phosphorus is more than sulphur. why? ​

Answer 1

Answer:

It is because of the stability of phosphorus is more than that of sulphur.

P= [Ne]3s^2 3p^3

S = [Ne]3s^2 3p4

Explanation:

As half filled p^3 and completely filled orbitals are p^ 6 are more stable then p^4 so that's why this stability Phosphorus has more 1st I.E than less stable element i.e Sulphur

Answer 2

Answer:

There are three competing factors for which the ionisation potential of sulphur lower than phosphorus: 1. The effective nuclear charge 2. The size of the atom and the force of attraction according to Coulombs law 3. A pair of electrons in an orbital In case of phosphorous and sulfur phosphorous has the greater ionization energy which means that it takes more energy to remove an electron from a phosphorous atom which means that the electrons are lower in energy even though the atom is larger and sulfur has a greater effective nuclear charge. This is what we call as stable half filled configuration of phosphorus.