Page 3 - LN 5

With increase in nuclear charge attraction between the nucleus and

valence electron is more,so an electron can easily add hence more energy is
released,so electron gain enthalpy is more negative.

 Electronic configuration :

Elements having exact half filled or full filled orbitals are very stable.So
energy to be supplied to add an electron.So they have positive electron gain

enthalpy.

 Variation in a group :

When we move from top to bottom in a group atomic size increases thus
electron gain enthalpy decreases i.e. less negative.

 Variation along a period :

When we move from left to right in a period atomic size decreases,nuclear
charge increases.So electron can easily be accepted by the atom, so electron

gain enthalpy is more negative.

 Electro negativity :

The tendency of an atom to attract the shared pair of electron in a covalent

bond is called electro negativity.

 Factors on which it depands :

(1) Atomic size :

Less the size of the atom, more its electro negativity.

(2) Nuclear charge :

Higher the nuclear charge more the electro negativity.

(3) Oxidation state :

More the charge on cation, more the electro negativity.

 Oxidation state :

In the same group the elements have same oxidation state.