Kinetic Particle Model of Matter (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Physics): Flashcards

False.

The particles in a gas are further apart than the particles in a liquid — about 10 times further apart in each direction.

The particles in a liquid are free to slide past one another.

The particles in a gas are widely separated and move about randomly at high speeds.

The particles in liquids and gases are randomly arranged.

False.

The particles in a solid are arranged in a regular pattern. The particles in a liquid are randomly arranged.

• Solids have a high density

• Liquids have a medium density

• Gases have a low density

The particles in a gas have the most energy. They are energetic enough to have overcome the intermolecular forces of attraction.

The particles in a solid have the least energy. They are not energetic enough to overcome the strong intermolecular forces holding them in place, so they only vibrate in position.

The particles in a liquid have enough energy to partially overcome the intermolecular forces of attraction. They have enough energy to slide past one another, but not enough to completely overcome the forces holding them close together.

The word particles can refer to:

• atoms

• molecules

• ions

• electrons

As the temperature of a gas increases:

• the average speed of the particles increases

• the particles have more kinetic energy

True.

The pressure exerted by a gas on its container depends on its temperature because the particles gain kinetic energy as the temperature increases.

Absolute zero is the lowest temperature possible. At absolute zero (0 K) the particles would not be moving, so they would not exert any pressure.

Absolute zero is −273 °C, which is 0 K.

True.

0 °C = 273 K, and an increase of 1 °C is equal to an increase of 1 K. Therefore, 10 °C = 283 K.

Pressure is defined as the force per unit area.

The equation for pressure is

Where:

• = pressure, measured in pascals (Pa)

• = force, measured in newtons (N)

• = area, measured in metres squared (m²)

• Gas particles move about randomly and collide with the walls of the container

• These collisions produce a force at right angles to the wall

• Pressure is force per unit area, so the force of these collisions exerts a pressure on the walls

Brownian motion is the random movement of particles in a liquid or gas produced by large numbers of collisions with smaller particles which are often too small to see.

False.

Brownian motion is evidence supporting the kinetic theory of matter.

False.

Water molecules, and the atoms and molecules in air, are too small to be seen under a microscope. Only the larger particles, such as pollen or smoke, can be seen moving.

Light, fast-moving atoms and molecules in the air collide with the larger pollen particles, giving them a nudge which changes their speed and direction randomly.

The presence of light, fast-moving molecules in a gas is inferred from the observed motion of the larger particles.

If the temperature of a gas remains constant, the pressure increases when the volume is decreased.

When a gas is compressed, the molecules hit the walls of the container more frequently. This creates a larger overall net force on the walls, which increases the pressure.

If the temperature of a gas in a balloon remains constant, the volume increases when the pressure is decreased.

If the volume of a gas remains constant, the pressure increases when the temperature is increased.

When a gas at constant volume is heated, the average speed of the molecules increases, so they collide with the container walls more often and with greater force.

True.

At constant volume, the pressure of a gas is directly proportional to its temperature, so the graph is a straight line.