Science Made Simple: What Is Plasma?

What Is Plasma?
Plasma is one of the four fundamental states of matter, alongside gases, liquids, and solids. While most people don’t think about plasma in their daily lives the way they think about other states of matter, plasma constitutes 99% of the visible matter in the universe. This includes astrophysical plasma found in outer space, such as within nebulae and stars like the Sun.

In plasma, some of the electrons separate and become free from neutral atoms (atoms that have an equal number of protons and electrons and thus a neutral charge). The resulting free electrons make plasma different from the other states of matter, where the electrons remain closely held to nuclei.

When the atoms in plasma separate from their negatively charged electrons, they no longer have a neutral electrical charge. Instead, the atoms become ions—positively charged particles. Therefore, plasma is an ionized state made up of positively charged ions and negatively charged electrons.