Question

part a: observations

1. start with the substance as a solid.

○ what do the particles look like?
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○ what happens when you slowly increase the temperature?
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○ at what point do you notice a change of state? (describe)
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1. now change the substance to liquid and begin at a moderate temperature.

○ describe the movement of particles in the liquid state.
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○ what happens when you increase the temperature further?
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○ what happens when you decrease the temperature?
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1. finally, start with the substance as a gas.

○ describe how the particles behave in the gas state.
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Explanation:

• Solid State:
• Particles are closely packed in an orderly arrangement.
• When temperature is slowly increased, particles vibrate more vigorously.
• Change of state (melting) occurs at the melting point when solid turns to liquid.
• Liquid State:
• Particles are close but can move past each other (flow).
• Further temperature increase makes particles move faster (more kinetic energy), may lead to evaporation or boiling.
• Decreasing temperature slows particle movement, may lead to solidification (freezing) at freezing point.
• Gas State:
• Particles are far apart, move freely and randomly at high speeds.

Answer:

1.

• Particles in solid: Closely - packed, orderly.
• When temp increased: Vibrate more.
• Change of state: At melting point (solid → liquid).

2.

• Liquid particles: Move past each other (flow).
• When temp further increased: Move faster (evaporate/boil).
• When temp decreased: Slow down (freeze).

1. Gas particles: Move freely, randomly, fast, far apart.