States of Matter
The Changing World Around You
Matter is all around us—it makes up everything! Whether it’s the solid ground beneath your feet, the water in your bottle, or the air you breathe, matter exists in three main states: solid, liquid, and gas. But here’s the cool part—matter can change between these states when energy, specifically heat, is added or removed. Let’s dive in and explore how this works!
The Basics of Matter
All matter is made up of tiny particles called atoms, which group together to form molecules. These molecules are held together by chemical energy and are always in motion. The energy they have because of this motion is called kinetic energy. Depending on how much kinetic energy particles have, matter takes one of three forms:
Solids: The particles are tightly packed together and barely move, vibrating in place. Solids have a fixed shape and volume. Think of ice or a brick—they keep their shape unless you apply force.
Liquids: Here, particles are more loosely packed and can flow around each other. Liquids take the shape of their container but keep the same volume. Ever noticed how water in a glass stays the same size no matter what? That’s a liquid at work.
Gases: The particles in gases are spread far apart, moving quickly and freely. Gases have no definite shape or volume. They’ll expand to fill any container they’re in—like the air in a balloon.
How Does Matter Change State?
The secret to changing states is heat energy. By adding or removing heat, you can make solids, liquids, and gases transform into one another. Let’s look at each change more closely.
Melting
When heat is added to a solid, its particles start vibrating faster and move further apart. Eventually, the solid changes into a liquid. This process is called melting. Think of ice cubes on a hot day—they melt into water as heat makes the particles move faster.
Evaporation and Boiling
Adding even more heat to a liquid makes the particles speed up further. Some particles escape into the air, turning into gas. This is evaporation. It happens all the time, like when puddles dry up in the sun. If heat is added very quickly, the liquid boils and changes rapidly into gas—this is boiling. A boiling pot of water turning into steam is a perfect example.
Condensation
When gas particles lose heat, they slow down and come closer together, forming a liquid. This is condensation. Ever noticed water droplets on the outside of a cold drink? That’s water vapour from the air cooling and condensing into liquid water.
Freezing
When a liquid loses enough heat, its particles slow down so much that they stick together tightly, forming a solid. This is freezing. For example, water in the freezer becomes solid ice as it cools.
Sublimation and Deposition
Some materials can skip a state entirely! In sublimation, a solid changes directly into a gas without becoming a liquid first. Dry ice (frozen carbon dioxide) does this, releasing a spooky fog. The reverse is deposition, where a gas turns straight into a solid, like frost forming on a cold window.
Why Does Heat Cause These Changes?
Heat is a type of energy. When you add heat, particles absorb that energy and move faster, increasing their kinetic energy. Removing heat has the opposite effect—particles slow down, and their kinetic energy decreases. This energy shift is what causes the particles to rearrange and change states.
Conservation of Mass
One amazing fact about state changes is that they don’t create or destroy matter. This is because of the law of conservation of mass, which says that the amount of matter stays the same no matter what state it’s in. If you melt ice cream, freeze it again, and repeat the process, you’ll always have the same amount of ice cream—just in different forms!
