Question

elements are boron ,carbon, nitrogen and oxygen .now arrange them in incresing order of electron gain enthalpy and explain the reson also for the arrangement ?

Answer 1

Oxygen wants 2e-
Boron donate 3e-
Nitrogen wants 3e-
Carbon wants 4e-(by covalent bonding)

along periods left hand side has metals with donating capacity of 1,2or3e- such as boron with atomic no. 5
electronic configuration=2,3
needs 5e- to complete octed state but elements can donate 1,2or 3e- therefore no one give him 5 e- so he donate 3e- and complete his douplet state.
carbon has atomic no. 6
e.cf=2,4
needs 4e-to complete octed state
but no one give him so he complete octed state by covalent bond.

Nitrogen atomic no. 7
e.cf=2,5
needs 3e- to complete octed state he get 3e- by another metal.

Oxygen Atomic no. 8
e.cf=2,6
needs 2e- to complete octed so he get 2 e- from another metal.