particle theory and states of matter
- Created by: tia5sos
- Created on: 26-11-20 18:22
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- particle theory and states of matter
- particle theory is a way of explaining matter
- 1. in particle theory, you can think of the particles that make up matter as tiny balls. You can explain the ways that matter behaves in terms of how these tiny balls move, and the forces between them.
- 2. three states of matter are solid (e.g. ice), liquid (e.g. water) and gas (e.g. water vapor).
- the particles of a substance in each state are the same - only the arrangement and energy of the particles are different. If you can reverse a change of state, the particles go back to how they were before.
- so physical changes e.g. melting or boiling, are different from chemical changes
- the particles of a substance in each state are the same - only the arrangement and energy of the particles are different. If you can reverse a change of state, the particles go back to how they were before.
- in a solid - strong forces of attraction hold the particles close together in a fixed regular arrangement
- the particles don't have much energy in their kinetic energy stores so they can only vibrate about their fixed positions.
- in a liquid - the force of attraction between the particles are weaker. The particles are close together but can move past each other and form irregular arrangements
- They have more energy in their kinetic energy stores than the particles in a solid - they move in random directions at low speeds
- in a gas - there are almost no forces of attraction between the particles
- particles have more energy in their kinetic energy stores than those in liquids and are free to move - travel in random directions at high speeds
- 3. the energy in a substances thermal energy store is held by its particles in their kinetic energy stores - this is what the thermal energy store actually is
- 4. when you heat a liquid, the extra energy passes into the particles' kinetic energy stores, making them move faster
- eventually, when enough of the particles have enough energy to overcome their attraction to each other, big bubbles of gas form in the liquid - this is boiling
- 5. it's similar when you heat a solid. The extra energy makes the particles vibrate faster until eventually the forces between them are partly overcome and the particles start to move around - this is melting
- 4. when you heat a liquid, the extra energy passes into the particles' kinetic energy stores, making them move faster
- density of a substance varies with state but mass doesn't
- 1. provided you're working with a closed system (i.e. no particles can escape, and no new particles can get in) the mass of a substance isn't affected when it changes state.
- the mass of a substance is the mass of its particles, and the particles aren't changing, they're just being rearranged
- 2. However, when a substance changes state its volume does change. The particles in most substances are closer together when they're a solid than a liquid...
- (ice and water are an exception), and are closer together when they're a liquid than a gas (see diagrams)
- 3. since density = mass divided by volume, then density must change too. Generally, substances are most dense when they're solids and least dense when they are gases.
- 1. provided you're working with a closed system (i.e. no particles can escape, and no new particles can get in) the mass of a substance isn't affected when it changes state.
- particle theory is a way of explaining matter
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