Why are electron affinity of halogens so high?
Answers
Electron affinity is actually the likelihood of gaining an electron by he neutral atom. It is the change in the energy of neutral atom when an electron enters in it to form a negative ion. In the periodic table, halogens are present on the left of the noble gases. They include five nonmetallic elements that make the group 17. As the electron affinity increases from left to right in a period, hence halogens have high electron affinities because while moving from left to right in a period, attraction between the nucleus and electrons increase, hence electron affinity is increased.
Electron affinity is the amount of the energy released while converting a neutral isolated gaseous atom into negatively charged ion.
Electron affinity is the negative of the electron gain enthalpy.
Electron affinity depends upon the Nuclear charge. It is directly proportional to it. If the Nuclear charge increases, then the Electron affinity also increases.
Now, Halogens are those non-metals which are present in the corner of the periodic table just before the Noble gases. In Period, they are having second last position.
When we move across the period, nuclear charge increases due to which electron affinity also increases.
Hence, the Electron affinity of the Halogens are high.
Although, Noble gases which lie at the corner just after the halogens have positive electron affinity, means they don't lose the energy when electron is added to them, but they require some energy because they are having full filled orbitals, and hence, new electron coming will be filled in upper orbitals which will create the unstability.
Hope it helps.