Particle model

Solid: Particles are closely packed in a regular arrangement. They are very close together with strong intermolecular forces. Particles vibrate about fixed positions.

Liquid: Particles are closely packed but in a random arrangement. The separation is slightly greater than in solids with weaker intermolecular forces. Particles move around and slide past each other.

Gas: Particles are widely spaced in a random arrangement. The separation is large with negligible intermolecular forces. Particles move randomly at high speeds.

1. Arrangement: In a liquid, particles are close together and in a random arrangement, whereas in a gas, particles are widely spaced and in a random arrangement.

2. Motion: In a liquid, particles can move around and slide past each other, while in a gas, particles move randomly at high speeds.

As temperature increases, the particles move faster and possess greater kinetic energy. Conversely, as temperature decreases, the particles move slower and have less kinetic energy.

At absolute zero (-273°C or 0 K), the particles possess the *least* possible kinetic energy. They are not stationary, but their motion is minimal due to the minimal energy in the system.

As the temperature approaches absolute zero, the motion of the particles decreases and the kinetic energy of the particles is minimised.

Gas particles are in constant, random motion. These particles collide with the walls of the container. Each collision exerts a small force on the wall. The pressure is the total force exerted by all the particles over the area of the wall. More frequent and/or more forceful collisions result in a higher pressure.

1. Increase the temperature of the gas. This increases the average kinetic energy of the particles, leading to more frequent and more forceful collisions with the container walls.
2. Decrease the volume of the container. This increases the frequency of collisions with the container walls as the particles have less space to move around in.

Description: Brownian motion is the random, erratic movement of microscopic particles suspended in a fluid (liquid or gas). These particles can be pollen grains in water, or smoke particles in air.

Explanation: The random movement of the larger particles is caused by collisions with the much smaller, invisible particles of the fluid. These collisions are uneven, resulting in a net force that causes the larger particle to move randomly. This supports the kinetic particle model which states that matter is made up of constantly moving particles. The observable motion of the larger particles is indirect evidence of the motion of the smaller fluid particles.

1. The pollen grains move randomly.
2. The pollen grains move erratically, changing direction frequently and unpredictably.

The pollen grains move randomly and erratically in all directions (Brownian motion). This is because the water molecules are constantly moving and colliding with the pollen grains from all sides. Since the water molecules are much smaller and invisible, their movement can only be inferred by observing the movement of larger pollen grains. Uneven collisions cause jerky, random movements.

The random movement is caused by collisions between the smoke particles and the air molecules. The air molecules are in constant, random motion and collide with the smoke particles. These collisions are uneven, resulting in a net force that causes the smoke particles to move in a random, jerky manner.

Solids have a fixed shape and volume because the particles (atoms, molecules, or ions) are held together by strong forces in a fixed arrangement. They vibrate in place but cannot move past each other.

Gases have no fixed shape or volume because the particles have weak forces between them, are widely spaced, and move randomly at high speeds. They can easily move past each other and fill any available space.

Ice at -10°C: Particles are tightly packed in a regular lattice structure, vibrating around fixed positions. There is limited movement, and the forces between the particles are strong.

Liquid water at 10°C: Particles are still close together, but the arrangement is less ordered. Particles can move around each other. The particles have more kinetic energy and vibrate and move more, and the forces between the particles are weaker.

Pressure = Force / Area
Pressure = 4.0 N / 0.01 m²
Pressure = 400 N/m² = 400 Pa

The pressure is the force exerted per unit area.

The gas pressure is due to the countless collisions of gas particles with the container walls. Each collision exerts a small force on the wall. The pressure is defined as the total force exerted by these collisions per unit area of the wall. More frequent and/or more forceful collisions result in a higher pressure.

The pollen grains exhibit random, jerky movements (Brownian motion). This is because water molecules, which are constantly moving, collide with the pollen grains from all directions. These collisions are uneven, resulting in a net force on the pollen grain, causing it to move randomly.

An atom is a fundamental, indivisible (chemically) component of matter. A pollen grain, however, is a microscopic particle comprised of numerous molecules, which are in turn made of many atoms bound together. A pollen grain is much larger and more complex than a single atom or molecule.