Write an equation that shows the formation of a selenide ion from a neutral selenium atom

Se + 2e- => Se-2

Explanation:

Ions are electrically charged particles, formed due to the gain or loss of electrons by an atom.

There are two types of ions cations and anions. An element that loses their electrons and forms positive ions are cations while metals and element that gains one or more electrons and forms negative ions are anions.

Selenium is an atom with atomic number 34 and represented as Se. The electronic configuration of Se is  1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p4. Selenium will gain 2 more electrons to complete it p orbital and form an ion Se-2.

The equation is as below:

Se + 2e- => Se-2