A change in which no new substances are formed, such as a change in state, e.g. melting.

When a reaction takes place and atoms or ions in the reactants are rearranged to make new products/substances.

Predicting states of matter

Chemistry

The particle model

State changes: fundamentals

State changes: evaporation and sublimation

Pure substance

Heating and cooling curves

Heating curves: practical

In the Separating Substances unit, pupils will build on their knowledge of states of matter to learn about different techniques for separating mixtures.

In the Solid, Liquid and Gas States and Changes of State unit, pupils learned about the properties of different states of matter and how particles move during changes of state.

This unit covers the particle model, states of matter, and changes between them, distinguishing physical from chemical changes. It explains the concept of purity in scientific terms, using melting point data to identify pure and impure substances, and explores the limitations of the particle model.

States of matter

Changes of state, such as when a substance in the solid state becomes a substance in the liquid state, do not involve the formation of new substances, so these are {{}} changes.

In the main image, the important information has been replaced with grey boxes. Which of the three images below is the best representation of a chemical change of substances in the same state?

Starting from a substance in the gas state, sort the states and the temperatures at which changes of state happen in order?

the colour of the particles: green is a colder colour than pink

the direction of the arrows: different arrows going in all directions

the shading of the particles: darker means stronger

the thickness of the arrows: thinner means weaker

In the image below, what indicates that substance A has a lower melting point than substance B?

it has more than one type of atom in its molecules

it has strong covalent bonds in the molecules

it has stronger intermolecular forces between the particles

it has the biggest particles and they do not move

Three balloons are filled with neon, methane and oxygen, respectively. Why would you expect the substance in the methane filled balloon to have the highest boiling point?

At which temperature are **all** these substances in a liquid state?

do not take the shape of the container they are in.

have larger particles than **all** substances in a liquid state.

have particles which have no energy at all.

have particles which vibrate around their fixed positions.

Which of the following statements can correctly finish this sentence?: Substances in a solid state...

at boiling point can form bubbles of the substance anywhere in the liquid.

have particles at the surface which may have enough energy to leave.

have particles which can move around and over each other.

take the shape of the whole of the container they are in.

Which of the following statements can correctly finish this sentence?: Substances in a liquid state…

are formed in the bubbles inside a liquid at boiling point

have particles which are not attracted to each other at all, ever

have particles which can escape an open container to fill all the space

take the shape of the container they are in

Which of the following statements can correctly finish this sentence?: Substances in a gas state…

As particles gain energy, they are able to overcome the {{}} between them.

Which aspects of a particle change when a substance’s state of matter changes?

temperature where substance changes from liquid state to gas state

temperature where substance changes from gas state to liquid state

temperature where substance changes from liquid state to solid state

temperature where substance changes from solid state to liquid state

Match the following terms to their definitions.

Predicting states of matter

Lesson outcome