Question

Which of the following is/are correct ?

• A. An element which has higher electronegativity always has a higher electron gain enthalpy
• B. Electron gain enthalpy is the property of an isolated atom
  
• C. Electronegativity is the property of a bonded atom
  
• D. Both electronegativity and electron gain enthalpy are usually directly related to nuclear charge and inversely related to atomic size

Answer 1

Answer: (B), (C), (D)

Both electronegativity and electron gain enthalpy are usually directly related to nuclear charge and inversely related to atomic size

Explanation:
(a) Cl has a higher electron gain enthalpy than F, F is the most electronegative element.
(b) Electron gain enthalpy is the property of an isolated gaseous atom.
(c) Electronegativity is the property of a bonded atom to attract a shared pair of electrons towards itself.
(d) More the effective nuclear charge, more the attraction between nucleus and outermost electrons. That is why electronegativity and electron gain enthalpy increases along the period from left to right.
As the atomic size increases i.e. distance between nucleus and valence shell increases, the attraction between nucleus and valence electrons diminishes hence both properties usually decrease from top to bottom along the group.