What is electron gain enthalpy?How does it vary in group and period?explain.
ELECTRON gain enthalpyWhen an isolated gaseous atom accepts an electron to form a monovalent gaseous anion, enthalpy change takes place and it is known as electron gain enthalpy. In simple words, we can say that when an isolated atom gains an electron and in energy is either released or absorbed. And this amount of energy is known as electron gain enthalpy.Higher the size of an atom, lower is its electron gain enthalpy and vice versa.Higher the effective nuclear charge, higher is electron gain enthalpy and vice versa.vary in group and period in a periodic tablein a period size decreases from left to right and hence electrons are more tightly held to the nucleus. so electron gain enthalpy increases across a period .down the period size increases and thus in general electron gain enthalpy decreses
Electron Gain Enthalpy is defined as the enthalpy change taking place when an isolated gaseous atom accepts an electron to form a monovalent gaseous anion.
Variation across a period Tends to become more negative as we go from left to right across a period. Because going from left to right across a period, tendency of the element to accept the electron increases. And hence a large amount of energy is released or electron gain enthalpy becomes more negative. For example fluorine has more negative electron gain enthalpy as compared to boron present in same period.
Variation down a group Becomes less negative on going down the group. On going down the group, element's tendency to accept an electron decreases. For example, iodine has less negative electron gain enthalpy than fluorine present in the same group.
as we move across the period electronegativity increases due to which e- gain enthaly also increases
and as we movw down thw group,electopositivity increases and hence e-negativity decreases