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States of Matter

We know that matter is everything that has mass and takes up space. Matter is made up of atoms and molecules and can be categorized into different types. Matter also has different states.

clouds (gas), the ocean (liquid), space and stars (plasma), and a brick wall (solid)

Watch the video States of Matter (3:03) below to learn more.

States of Matter: Video Short | Science Trek downloaded from PBS LearningMedia, https://www.pbslearningmedia.org/resource/idptv11.sci.phys.matter.d4kmat/states-of-matter/. Rights to use this asset do not expire. Asset Copyright: ©2005 Idaho Public Television. All rights reserved. Source: Science Trek: "States of Matter". Project funded by: Laura Moore Cunningham Foundation. See full license here.

4 States of Matter

The four states of matter are:

  1. Plasma
  2. Solid
  3. Gas
  4. Liquid

the sun (plasma), rock cliffs (solid), smoke from a factory (gas), and a waterfall (liquid)

Solids

Solids are hard and maintain their own shape.

container with particles closely and uniformly packed together

Liquids

Liquids are fluid and take on the shape of their container.

container with particles close together in a jumble

Gases

Gases move freely and take the shape of their container.

container with particles floating separately around each other

Plasma

Plasmas are similar to gases, but their atoms are different. On Earth, we find plasma in lightning. Plasma makes up most of the matter in the universe, including the stars.

container with plasma particles floating around positive and negative charges


Physical States

The physical state of the atoms and molecules determine the state of the matter. There are distinct differences in the states of matter.

a helium balloon (a gas) with the description 'Gases take the shape and volume of their container. Particles are farther apart.' a container of water (a liquid) with the description 'Liquids take the shape of their container. They have a fixed volume.' and several blocks of salt (a solid) with the description 'Solids maintain their shape, no matter the container, and have a fixed volume.

Examples of three of the four physical states.


Phase Changes

Because matter is based on the physical state of its atoms and molecules, they can change from one form to another. This is called a change of state or phase change.

  • A solid can be heated to become a liquid.
  • A liquid can be heated to become a gas.

We can see the change from solid to liquid, but we cannot always see the liquid change to a gas.

phase change diagram showing a liquid changing to a gas (evaporation), a gas becoming a liquid (condensation), a gas becoming a solid (deposition), a solid becoming a gas (sublimation), a solid becoming a liquid (melting), and a liquid becoming a solid (freezing)

Matter can change state through processes like evaporation, condensation, and the others listed.


Chemical State is Stable

Even though matter changes physical states, its chemical state remains stable and does not change.

A good example of matter changing physical states but keeping its chemical state is water.

  • Water can be a liquid and freeze to form a solid (ice).
  • Ice can melt back to liquid water.
  • Both can evaporate to become a gas.

During these changes in physical state, the chemical state does not change. It is always water (H2O).


Temperature and Plasma

Temperature affects the physical state of matter. As temperature increases, a gas can ionize to become plasma. Conversely, as temperature decreases, plasma can undergo recombination (also called deionization) to become gas.

chart of phase changes showing increase in energy and temperature: solid (lowest energy and temperature) to a liquid (second lowest energy and temperature) (melting), liquid to solid (freezing), solid to gas (next highest energy and temperature, between liquid and plasma) (sublimation), gas to solid (deposition), gas to liquid (condensation), liquid to gas (vaporization), gas to plasma (highest energy and temperature) (ionization), and plasma to gas (recombination)


Particulate Nature of Matter

To learn more, complete The Particulate Nature of Matter activity.

Complete both parts:

  • The Tutorial
  • The Problem Set

Pay close attention to how the particles in solids, liquids, and gases move, as you will need this information to complete the Task.