Trends in Physical Properties - Ionization Enthalpy or Ionization Energy (IE) or Ionization Potential (IP)

The first ionization enthalpy values (in kJmol^–1) of group 13 elements are:-

How would you explain this deviation from the general trend?

Assertion (A): Generally, ionisation enthalpy increases from left to right in a period.

Reason (R): When successive electrons are added to the orbitals in the same principal quantum level, the shielding effect of inner core of electrons does not increase very much to compensate for the increased attraction of the electron to the nucleus.

Among the second period elements the actual ionization enthalpies are in the

order Li < B < Be < C < O < N < F < Ne.

Explain why Be has higher Δ_iH than B?

Nitrogen has positive electron gain enthalpy whereas oxygen has negative. However, oxygen has lower ionisation enthalpy than nitrogen. Explain.

Which one of the following statements is incorrect in relation to ionization enthalpy?

The decreasing order of the second ionization potential of K, Ca and Ba is ______.

For the gaseous reaction, \[\ce{K_{(g)} + F_{(g)} -> K^+_{ (g)} + F^-_{ (g)}}\], ΔH was calculated to be 19 kcal/mol under conditions where the cations and anions were prevented by electrostatic separation from combining with each other. The ionisation energy of K is 4.3 eV. The electron affinity of F is ______. (in eV)

Arrange the elements \[\ce{N, P, O}\] and \[\ce{S}\] in the order of increasing first ionisation enthalpy. Give reason for the arrangement assigned.