Give reason: Negative Electron gain enthalpy of Nitrogen(Z=7), Phosphorous

The negative electron gain enthalpy of Nitrogen (Z=7) and Phosphorus can be explained by the following reasons:

1. Small atomic size: Nitrogen and Phosphorus have relatively small atomic sizes. This means that when an additional electron is added to their outermost energy level, there is a high electron-electron repulsion due to the close proximity of the electrons. This repulsion makes it energetically unfavorable for the atom to accept an additional electron, resulting in a negative electron gain enthalpy.

2. Stable electronic configuration: Nitrogen and Phosphorus have stable electronic configurations in their respective outermost energy levels. Nitrogen has a half-filled p orbital (2p3) and Phosphorus has a completely filled p orbital (3p6). These stable configurations provide a certain level of stability to the atoms, making it difficult for them to accept an additional electron and resulting in a negative electron gain enthalpy.

3. High ionization energy: Nitrogen and Phosphorus have relatively high ionization energies, which means that a significant amount of energy is required to remove an electron from their outermost energy level. This high ionization energy indicates that the atoms have a strong hold on their electrons and are less likely to accept an additional electron, resulting in a negative electron gain enthalpy.

Overall, the combination of small atomic size, stable electronic configurations, and high ionization energies contribute to the negative electron gain enthalpy of Nitrogen and Phosphorus.