Electron affinity [ENDORSED]

[Lulu Almoshawah_2K]

I'm a little confused over what electron affinity is and how we calculate it. can someone help out please

[Riya 14B-2]

Hey!
To address the first part of your post, electron affinity is the change in energy when an electron is added to an atom in its gaseous state. In general, electron affinity increases going across a period and up a group of the periodic table.

[Shivani Sakthi 1l]

Hello! Electron Affinity is defined as the energy released when an electron is added to a gaseous atom. It revolves around the energy emitted from an electron when it is attracted to the nucleus, and thus pulled towards a lower energy level. This is why the periodic trend concerning electron affinity is a general increase as we move left to right on a period. This is because as the effective nuclear charge increases down a period, because the number of protons increases while the configuration of the shielding electrons stays the same, an added electron feels a greater pull towards the nucleus, giving off energy. However, if we look at a noble gas, the valence electron shell is already full. So when adding an electron, we are moving into another electron shell that is shielded (repelled) by the full lower electron shell. Therefore, the electron affinity goes to 0 because the nucleus is not attracted to the added electron. You can see this trend on #30 in the Week 3 Achieve HW problems. Kr has the lowest electron affinity, or the highest energy absorbed upon adding an electron because an electron is added to another energy level since KR already initially has a full shell. So adding an electron is not favorable. However, F has the highest electron affinity since we are transitioning to a more stable state by adding the electron, which is highly favorable.

[Benicio Rivera 1F]

Electron affinity is the energy change that results from adding an electron to a gaseous atom. For example, when a fluorine atom in the gaseous state gains an electron to form F⁻(g), the associated energy change is -328 kJ/mol.