Among the elements of second period i.e. from Li to Ne, pick out the elements:

(a) with the highest first ionisation enthalpy
(b) with the highest electronegativity
(c) with the largest atomic radius
(d) which is the most reactive non-metal
(e) which is the most reactive metal ?

The IE₁,  of carbon, is more than that of boron while its IE₂ value is smaller. Explain.

The first ionization enthalpy values (in kJ mol^-1) of group 13 elements are:
B       Al      Ga      In        Tl
801    577   579    558    589
How would you explain this deviation from the general trend?

Nitrogen and phosphorus have high value of ionisation enthalpies. Explain.

How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium? 

Be and Mg have high value of ionisation enthalpies. Explain.

The first (IE₁) and second (IE₂) ionisation enthalpies (kJ mol^-1) of a few elements by Roman numerals are as shown:

which of the above elements is likely to be:
(i) a reactive metal
(ii) a reactive non-metal
(iii) a noble gas
(iv) a metal that forms a stable binary halide of the formula AX₃ (X = halogen).

Which of the following pairs of elements would you expect to have lower first ionisation enthalpy? Explain your answer:

(a) Cl or F

(b) Cl or S

(c) K or Ar

(d) Kr or Xe.

Arrange the following in order of increasing ionisation enthalpies and assign reason:

(i) K⁺, Ar, Cl^-    
(ii) Fe, Fe²⁺, Fe³⁺