States of matter
The particle model of solids, liquids and gases, why gases can be compressed, the six changes of state, and why the temperature stays flat on a heating curve while a substance melts or boils. With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
Practice
- Check yourself: States of matter – Type the missing words, put the steps in order and write a short answer. No multiple choice: you have to remember it.
Transcript
All matter is made of tiny particles. Matter can be a solid, a liquid or a gas. We call these the three states of matter.
In a solid, the particles touch each other in a regular pattern. They cannot move around. They only vibrate on the spot. So a solid keeps its shape and its volume.
In a liquid, the particles still touch, but they are not in a pattern. They slide past each other. So a liquid flows and takes the shape of its container.
In a gas, the particles are far apart and move very fast in all directions. So a gas has no fixed shape or volume. It fills its container.
Look at the pushing test. A liquid is very hard to compress, because its particles already touch. There is no space to squash them into.
A gas is easy to compress. There is a lot of empty space between the particles, so they can be pushed closer together.
When we heat a solid, the particles get more energy. At the melting point, the solid melts and becomes a liquid. When we cool the liquid, it freezes and becomes a solid again.
At the boiling point, the liquid boils and becomes a gas. When we cool the gas, it condenses and becomes a liquid. Evaporation also makes a gas, but only at the surface of the liquid.
A few solids, such as dry ice, change straight into a gas. We call this sublimation.
Here is a heating curve for water. We heat the ice at a steady rate. The temperature rises, then it stays at zero degrees Celsius while the ice melts.
After that the temperature rises again. It stays at one hundred degrees Celsius while the water boils. During a change of state, the energy separates the particles, so the temperature stays the same.
Remember. In a solid, the particles touch and vibrate. In a liquid, they touch and slide. In a gas, they are far apart and move fast. A gas is easy to compress. And during a change of state, the temperature stays constant.
More in this series
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Twelve key words for IGCSE Co-ordinated Sciences topic C1 (the particulate nature of matter), with the Vietnamese meaning, how to say each word, a picture and an example. Ends with a test section, and a typing trainer on the site that also practises twelve general science words.
2:36Diffusion
What diffusion is, why particles spread from high to low concentration, how temperature and particle mass change the speed, the ammonia and hydrogen chloride tube, and Brownian motion. With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
5:36C1 quiz: particulate matter
Ten think-time questions on solids, liquids and gases, the changes of state, the heating curve, diffusion and particle mass.