Everything you can touch and see is made of matter. Matter is anything that has mass and takes up space (volume). But matter doesn't always look the same—it can exist in different forms, or states. The four most common states of matter are solid, liquid, gas, and plasma.
The state of a substance is determined by how its particles (atoms or molecules) are arranged and how they move.
In a solid, particles are packed tightly together in a fixed arrangement. They can't move around freely; they can only vibrate in place. This is why solids have a definite shape and a definite volume. A block of ice is a solid. It doesn't change its shape or size if you move it from a bowl to a plate.
In a liquid, particles are still close together, but they are not in a fixed arrangement. They have enough energy to slide past one another. This is why liquids have a definite volume but an indefinite shape. A liquid will take the shape of its container. 100 mL of water is always 100 mL (definite volume), but it will look different in a tall glass versus a wide bowl (indefinite shape).
In a gas, particles are very far apart and move randomly and quickly. They have a lot of energy and are not attracted to each other. This is why gases have an indefinite shape and an indefinite volume. A gas will expand to fill whatever container it is in. The air in a room is a gas.
Plasma is the most common state of matter in the universe, but it's less common on Earth. It is a superheated gas. The particles have so much energy that the electrons are stripped away from the atoms, creating a mixture of charged ions and electrons. Stars, like our Sun, and lightning are made of plasma.
You can change a substance from one state to another by adding or removing thermal energy (heat).
Which state of matter has a definite volume but takes the shape of its container?
The process of a gas turning directly into a solid is called ________.
Describe the motion of particles in a solid.