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

The Plasma State

Plasma is known as the fourth state of matter. The other three states are solid, liquid and gas.

Almost everything is made up of atoms (your dog, your science book, this computer...). The atom has a nucleus which has a positive charge. Electrons orbit the nucleus. The electrons (which have a negative charge) are attracted to the nucleus. Remember, opposites attract! But sometimes something comes along that sets the electrons free from orbiting the nucleus. Really hot temperatures can do this! When electrons are no longer trapped in orbits around the nucleus, we have the plasma state.

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).

Last modified January 22, 2001 by Jennifer Bergman.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA