States of Matter - Definition, Examples, Facts & Quiz, FAQ, Trivia
Learn about solids, liquids, gases, and how they change in everyday life
What Are States of Matter?
Matter is anything that has mass and takes up space. It comes in three main forms or states:
Solids - Have a fixed shape and volume (like a book or an ice cube)
Liquids - Have a fixed volume but take the shape of their container (like water in a glass)
Gases - No fixed shape or volume, they expand to fill their container (like the air we breathe)
These states can change from one to another when we add or remove heat energy. This is called changing states of matter.
Science Fact!
There are actually more than three states of matter! Plasma is a fourth state found in stars and lightning, and scientists have discovered others in special conditions.
Solids
Solids are one of the three main states of matter. Here's what makes them special:
• They have a fixed shape - they don't change shape unless you force them
• They have a fixed volume - they take up the same amount of space
• The particles in solids are packed tightly together in a regular pattern
• The particles vibrate in place but don't move around freely
Examples of solids: Ice, rocks, books, pencils, desks, toys, and most things you can hold.
Hardness
Some solids are hard (like diamonds) while others are soft (like cotton)
Flexibility
Some bend easily (rubber) while others are rigid (brick)
Texture
Can be smooth (glass), rough (sandpaper), or somewhere in between
Strength
Some break easily (chalk) while others are very strong (steel)
Liquids
Liquids are another important state of matter. Here's what makes them special:
• They have a fixed volume but no fixed shape
• They take the shape of their container
• The particles are close together but can move around
• They can flow and be poured
• The surface of a liquid is always flat and level
Examples of liquids: Water, juice, milk, oil, honey, and soda.
Water Fact!
Water is special because it's one of the few substances that is naturally found as a solid (ice), liquid (water), and gas (steam) on Earth!
Viscosity
How thick or thin a liquid is (honey has high viscosity, water has low viscosity)
Surface Tension
The "skin" on a liquid's surface that makes some bugs able to walk on water
Density
How much mass is in a certain volume (oil is less dense than water so it floats)
Gases
Gases are the third main state of matter. Here's what makes them special:
• They have no fixed shape or volume
• They expand to fill their container completely
• The particles are far apart and move quickly in all directions
• They can be compressed (squeezed into smaller spaces)
• Most gases are invisible but we can feel them (like wind)
Examples of gases: Air (oxygen, nitrogen), helium in balloons, steam, carbon dioxide in soda bubbles.
Expansion
Gases spread out to fill any available space
Compressibility
Gases can be squeezed into smaller volumes
Diffusion
Gases mix evenly when placed together
Pressure
Gas particles constantly push on their container
Changing States of Matter
Matter can change from one state to another when we add or remove heat energy. These are called changes of state. There are six main changes to know:
Melting
Solid → Liquid (adding heat) - Ice melting into water
Freezing
Liquid → Solid (removing heat) - Water freezing into ice
Evaporation
Liquid → Gas (adding heat) - Water boiling into steam
Condensation
Gas → Liquid (removing heat) - Steam cooling into water droplets
Sublimation
Solid → Gas (adding heat) - Dry ice turning into carbon dioxide gas
Deposition
Gas → Solid (removing heat) - Frost forming from water vapor
These changes happen all around us every day! When you:
• Make ice cubes (freezing)
• Boil water for tea (evaporation)
• See your breath on a cold day (condensation)
• Watch snow disappear without melting (sublimation)
The temperature at which these changes happen is different for different substances.
States of Matter Quiz
Test your knowledge with these 5 questions covering all about states of matter!
Frequently Asked Questions
Here are answers to some common questions about states of matter:
States of Matter Trivia
Discover some amazing facts about states of matter!
Space Matter
99% of the visible universe is made of plasma, not solids, liquids, or gases! Stars, including our Sun, are giant balls of plasma.
Extreme Cold
At -273.15°C (-459.67°F), called absolute zero, molecular motion almost stops. Scientists have gotten within billionths of a degree of this temperature!
Water's Odd Behavior
Water is one of the few substances that expands when it freezes. This is why ice floats and why pipes can burst in winter.
Super States
Scientists have discovered states beyond solid, liquid, gas, and plasma, including Bose-Einstein condensates (formed at extremely cold temperatures) and quark-gluon plasma (found in particle accelerators).
