Question

changing state
describe what happens to the energy and speed of particles when a substance changes temperature.
heating a substance
the energy of the particles, causing them to
cooling a substance
the energy of the particles, causing them to
draw what happens to water (h₂o) particles when ice is heated. annotate your drawing to describe the spacing, energy, and speed of the molecules in each state.
expert study tip
annotating
adding extra explanations to a picture, diagram, or text is called annotating. it helps you understand information better as you read it. it also helps you pick out important information quickly when you start to revise. try it for yourself!
h₂o particles in a solid state
h₂o particles in a liquid state
h₂o particles in a gaseous state
heating
check your understanding
learning goal 1
i can recall that physical changes involve the same particles that have moved to new positions, sped up, or slowed down
i can describe physical changes in terms of the arrangement of particles

Explanation:

Step1: Heating a substance

When a substance is heated, energy is added to the particles. According to the kinetic - theory of matter, the added energy increases the kinetic energy of the particles. As a result, the speed of the particles increases.

Step2: Cooling a substance

When a substance is cooled, energy is removed from the particles. This decreases the kinetic energy of the particles, and thus the speed of the particles decreases.

Step3: Water particle states

• Solid state (ice): The $H_2O$ particles are closely packed in a regular pattern. They have low kinetic energy and vibrate in fixed positions.
• Liquid state: The $H_2O$ particles are closer together than in the gas state but are not in a regular pattern. They have more kinetic energy than in the solid state and can move around each other.
• Gaseous state: The $H_2O$ particles are far apart and move freely in all directions. They have high kinetic energy and high speed.

Answer:

Heating a substance: Increases; move faster
Cooling a substance: Decreases; move slower
For the drawing:

• In the solid state (ice), draw $H_2O$ particles closely packed in a regular lattice - like structure. Annotate: "Closely packed, low energy, slow - moving, vibrate in place".
• In the liquid state, draw $H_2O$ particles closer together but not in a regular pattern. Annotate: "Closer than gas, more energy than solid, can move around each other".
• In the gaseous state, draw $H_2O$ particles far apart. Annotate: "Far apart, high energy, move freely in all directions".