P1.1.2 Kinetic Theory

Question 1

In terms of arrangement and energy, describe how particles move in solids.

Answer 1

• Strong forces of attraction hold in the particles close together…
• …in a fixed, regular arrangement.
• The particles don’t have much energy…
• …so they can only vibrate about their fixed position.

Question 2

In terms of arrangement and energy, describe how particles move in liquids.

Answer 2

• There are weaker forces of attraction between the particles and while the particles are close together…
• …they can also move past each other, and form irregular arrangements.
• They have more energy than the particles in a solid…
• …so they move in random directions at low speeds.

Question 3

In terms of arrangement and energy, describe how particles move in gases.

Answer 3

• There are almost no forces of attraction between the particles and so they can move further apart than those in solids and liquids…
• …with an irregular arrangement.
• The particles also have more energy…
• …so are free to move, and travel in random directions, at high speeds.