Ion

An Ion is an atom that outer shell(s) of electrons, are missing an electron, or have an extra electron.

Each of the chemical elements in the periodic table, has an unique number of positively charged protons in its atomic nucleus. When an atom has the same number of negatively charged electrons electrons in its outer shell of electrons as it has proton's in its atomic nucleus, then that atom is electrically neutral. The positive and negative charges balance out.

Atoms that have lost an electron, or gained an extra electron, are said to be "ionized". Ions are very chemically reactive.

High energy, or high temperature, can strip or add electrons. When a large number of electrons jump from a cloud to the Earth, or vice versa, the energy discharge will leave the air ionized. The high temperature of a star, like Sol, our sun, leaves its atoms highly ionized.