Page 2 - LN 5

Ionization enthalpy increases as the penetration effect of electrons

increases. Penetration effect decreases in the order

s-subshell > p-subshell > d-subshell > f-subshell.

 Electronic configuration :

Stable electronic configuration i.e. in case of half-filled orbitals ionization
enthalpy is more.

 Variation in a group :

From top to bottom the atomic size increases, so ionisation enthalpy
decreases.

 Variation along a period :

From left to right in a period the effective nuclear charge increases, so
ionisation enthalpy increases.

 Electron gain enthalpy :

The energy released when a neutral isolated gaseous

atom accepts an extra electron to form corresponding anion is called

electron gain enthalpy.

 Successive electron gain enthalpy :

rd
nd
The amount of energy change when first, 2 and 3 electrons are added to
a neutral gaseous atom in order to form uni negative, bi negative and tri
negative ions respectively are called successive electron gain enthalpies.

 Factors affecting electron gain enthalpy :

 Atomic size :

With increase in atomic size electron gain enthalpy decreases because

distance between nucleus and valence electron increases, attractive force
increases.

 Nuclear charge :