Matter Particles & Mixing Explorer

All matter is made of tiny particles that are always moving. How they move and how close together they are determines whether something is a solid, liquid, or gas.

• Solid – particles are packed in a tight grid and vibrate in place
• Liquid – particles are close together but slide past each other
• Gas – particles are spread far apart and move quickly in all directions

When you add or remove heat, matter can change from one state to another. These are called phase changes.

• Melting – solid turns to liquid (add heat)
• Freezing – liquid turns to solid (remove heat)
• Boiling/Evaporating – liquid turns to gas (add heat)
• Condensing – gas turns to liquid (remove heat)

When you dissolve salt or sugar in water, the total mass does not change. The particles of the solute break apart and spread out among the water particles, but nothing is lost.

Key idea: matter is not created or destroyed when things mix, dissolve, or change state. The total mass before always equals the total mass after.

When you mix two things together, sometimes you get a new substance (chemical change) and sometimes you don't (physical change). Look for these clues.

• Signs of a new substance: color change, bubbles/gas, heat or light produced, hard to reverse
• Signs of just mixing: you can still see both materials, easy to separate, no gas or color change