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

Plasma is known as the fourth state of matter (the first three states being solid, liquid and gas).

Matter in ordinary conditions on Earth has electrons that orbit around the atomic nucleus. The electrons are bound to the nucleus by the mutual, electrostatic attractive force. If the temperature is high enough, the electrons (at least those of the outermost orbits) acquire enough kinetic energy to escape the atom's potential (similar to a spacecraft that escapes the Earth's gravitational pull). In this situation the electrons are no longer trapped in orbits around the nucleus. This is the plasma state, where a gas becomes a collection of negatively charged electrons which have escaped the pull of the nucleus and ions which are positively charged because they have lost one or more electrons.

The majority of the matter in the universe is actually found in the plasma state. This is because stars are made up of material 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