When electrons are added to an atom, the increased negative charge puts stress on the electrons already there, causing energy to be released. When electrons are removed from an atom, that process requires energy to pull the electron away from the nucleus. Addition of an electron releases energy from the process.

Frequency is the number of wave cycles passing a point per unit of time.

The SI unit used to measure frequency is the hertz (Hz).

A double bond is a bond between two atoms where each atom donates a pair of electrons. TRUE.