MCAT Flashcards: Electron Affinity

What is electron affinity? Ken Tao is an MCAT expert and explains that it’s the amount of energy associated with adding an electron to a neutral atom. A positive EA means that energy is required for the atom to gain the electron. A negative EA means that energy is released when the atom gains an electron.

Full Transcription

In this flash card video, we’re going to discuss “What is electron affinity?”

Electron affinity is the energy associated with adding an electron to an atom. A positive electron affinity means that energy is required for the electron to be added to the atom. A negative electron affinity means that energy is released when the electron is added to the atom.

You should know that a greater electron affinity is a more negative value. And that’s because, if you think about it, affinity means you like something. So an atom with a high electron affinity likes electrons, and when a species likes electrons, it becomes more stable. It reaches a lower energy state when it attains that electron. And that is reflected when that species releases energy when it gains an electron.

The periodic trend for electron affinity is that it increases going up and to the right across the periodic table.