Question

Halogens have high negative value of electron gain enthpy why

Answer 1

Halogens have a small size and high electron charge.

Their electronic configurations are ns2 and np5. Thus they have a high tendency to gain one electron to achieve a full filled outer most shell.

Since electron gain enthalpy is said to be negative when an electron is removed from an electron, it would be very high if 5 electrons are removed thus their values would be largely negative.