The Plasma State

Plasma: the negatively charged electrons (yellow) are freely streaming through the positively charged ions (blue). Image courtesy of General Atomics

In most cases, matter on Earth has electrons that orbit around the atom's nucleus. The negatively charged electrons are attracted to the positively charged nucleus. Remember, opposites attract! So the electrons stay in orbit around the nucleus. When temperatures get REALLY hot, the electrons can escape out of their orbit around the atom's nucleus. When the electron(s) leave, that leaves behind what scientists call a positively charged ion. This whole process is similar to a spacecraft that escapes the Earth's gravitational pull.

In summary, when electrons are no longer trapped in orbits around the nucleus, we have the plasma state. This is when a gas becomes a bunch of electrons which have escaped the pull of the nucleus and ions which are positively charged because they have lost one or more electrons.

Most of the matter in the universe is found in the plasma state. That is because stars contain so much of the matter in the universe (stars are so hot that their matter can only exist in the plasma state).