Electron Gain Enthalpy Of Elements In Modern Periodic Table

Electron gain enthalpy is the energy change that occurs when an atom accepts an electron. It is generally a negative value, indicating that the process is exothermic. The electron gain enthalpy of elements generally becomes more negative down a group and more positive across a period in the modern periodic table. This is because the effective nuclear charge increases down a group and across a period, making it more difficult for an atom to accept an electron. The exceptions to this trend are the noble gases, which have a complete valence shell and therefore have a very positive electron gain enthalpy.