States of Matter

Solids, Liquids, Gases & Plasma

Ice
Yuji Kotani / Getty Images

Matter occurs in four states: solids, liquids, gasses, and plasma. Often the state of matter of a substance may be changed by adding or removing heat energy from it. For example, the addition of heat can melt ice into liquid water and turn water into steam.

Solids

  • A solid has a definite shape and volume.
  • Examples of solids include ice (solid water), a bar of steel, and dry ice (solid carbon dioxide).

    Liquids

    • A liquid has a definite volume but takes the shape of its container.
    • Examples of liquids include water and oil.

    Gases

    • A gas has neither a definite volume nor a definite shape.
    • Examples of gasses are air, oxygen, and helium.

    Some introductory chemistry texts name solids, liquids, and gasses as the three states of matter, but higher level texts recognize plasma as the fourth state of matter.

    Plasma

    • Plasma has neither a definite volume nor a definite shape.
    • Plasma often is seen in ionized gasses. Plasma is distinct from a gas because it possesses unique properties. Free electrical charges (not bound to atoms or ions) cause the plasma to be electrically conductive. The plasma may be formed by heating and ionizing a gas.
    • Stars are made of plasma. Lightning is plasma. You can find plasma inside fluorescent lights and neon signs.

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      Helmenstine, Anne Marie, Ph.D. "States of Matter." ThoughtCo, Feb. 12, 2017, thoughtco.com/states-of-matter-p2-608184. Helmenstine, Anne Marie, Ph.D. (2017, February 12). States of Matter. Retrieved from https://www.thoughtco.com/states-of-matter-p2-608184 Helmenstine, Anne Marie, Ph.D. "States of Matter." ThoughtCo. https://www.thoughtco.com/states-of-matter-p2-608184 (accessed November 17, 2017).