Beginner Topic 222 of 1102 States of Matter & Solutions
Plasma
An ionized gas of free ions and electrons, the most common visible state of matter in the universe.
Practise States of Matter & Solutions All States of Matter & Solutions topics
In-depth explanation of Plasma
Plasma is an ionized gas in which atoms have lost electrons, leaving a mixture of positive ions and free electrons. It forms when a gas is heated to very high temperatures or placed in a strong electric field, which supplies enough energy to strip electrons from atoms. Because the charged particles are free to move, plasma conducts electricity and responds strongly to magnetic fields. Plasma is the most common form of visible ordinary matter in the universe, making up stars and much of the interstellar medium. On Earth it appears in lightning, flames and neon signs.
Going deeper: Plasma
Key ideas: Ionization requires energy at least equal to the ionization energy, about 13.6 eV for hydrogen, equivalent to temperatures of order 10^4 K or more. Plasmas are quasi-neutral overall, with equal positive and negative charge densities, and show collective behaviour such as plasma oscillations. Density and temperature span huge ranges, from cold neon-sign plasma to fusion plasma near 10^8 K.
Common mistakes and connections: Do not confuse plasma with a hot gas that is merely glowing; ionization fraction matters. A flame is only weakly ionized. Plasma is often called the fourth state but is not reached by a sharp phase transition. Connects to ionization energy, electrical conductivity and nuclear fusion in stars.
Visualization of Plasma
In a plasma, neutral atoms lose electrons to form ions such as H3O+ style charged species; shown is a positive ion, one of the charged particles in an ionized gas. The interactive lesson shows this as a live animation or chart.
Worked example and use case
The Sun is a hot ball of plasma in which hydrogen atoms are almost fully ionized in its core and outer layers.
Frequently asked questions about Plasma
What is Plasma?
An ionized gas of free ions and electrons, the most common visible state of matter in the universe.
Is Plasma a beginner, intermediate or advanced topic?
Plasma is a beginner topic in States of Matter & Solutions. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Plasma?
Study these earlier topics in States of Matter & Solutions first: States of Matter, Kinetic Molecular Theory.
What comes after Plasma?
The next topics in States of Matter & Solutions are Bose-Einstein Condensate and Pressure.
Can I practise Plasma with quizzes?
Yes. The interactive lesson includes a self-check question on Plasma, and the States of Matter & Solutions quiz draws on every topic in this area.
Where Plasma fits in States of Matter & Solutions
Plasma is topic 3 of 109 in States of Matter & Solutions.