A pure substance contains only one type of chemical

A mixture is a material that contains two or more different substances which can be physically separated

An impurity is a chemical that is found in a material in very small amounts, but can change the material's properties

Pure substances

Science

Mixtures: choosing equipment

Mixtures: equipment diagrams

Mixtures and solutions

Diffusion

Dissolving

Variables

Dissolving: scientific methods

Solubility: practical

Solubility: analysis

Saturated solutions

In the Separation Techniques unit, pupils will build on their knowledge of solutions to learn about methods for separating mixtures, including filtration, evaporation, distillation, and chromatography.

In the Solid, Liquid and Gas States and Changes of State unit, pupils learned to categorise substances into the solid, liquid or gas state and explored particle behaviour during changes of state.

This unit explores the concepts of pure substances, mixtures, and diffusion in liquids and gases. It emphasises accuracy, precision, and the use of appropriate techniques during investigations. The focus is on making predictions and recording reliable observations.

Solutions

Apparatus is a piece of equipment that is designed for a particular use.

Mass is the amount of matter in an object, usually measured in grams.

Volume is how much 3D space a material occupies.  It is usually measured in cm³.

A piece of equipment that is designed for a particular use.

A 2D representation of a piece of apparatus.

Use scientific drawings to show how equipment is set up for an investigation.

A solute is a substance that has dissolved into a solvent.

A solvent is a substance into which a solute dissolves.

When a solute dissolves, it is described as soluble.

When a solute and solvent combine, a solution forms.

The combined mass of starting materials equals the combined mass of the end products.

The movement of particles from an area where there are lots, until there is a random distribution of particles throughout a medium.

Happens without a clear pattern, making it unpredictable.

The random movement of particles in a fluid, due to colliding with particles in the surrounding medium.

A medium is usually a liquid or gas that other substances can mix into or move through, enabling other substances to mix or interact.

A fluid is a substance that flows or takes the shape of its container.  Liquids and gases can be described as fluids.

Occurs when a substance's particles separate and spread throughout the particles of a solvent resulting in it no longer being seen.

If a substance does not dissolve in a particular solvent, it is described as insoluble.

Melting occurs when a substance in the solid state is heated and its particles move into the arrangement of a substance in the liquid state.

A force of attraction is a pulling force that keeps things, such as particles, close together.

A mixture of an insoluble solid and liquid in which the solid particles are dispersed in the liquid and settle upon the mixture standing.

A variable is anything that can change or be changed in an investigation.

The independent variable is the variable that is changed during an investigation.

The dependent variable is the variable that is measured or observed during an investigation; it changes as a result of varying the independent variable.

A control variable is a variable that is kept the same or constant to ensure a fair test.

When only one variable is changed to affect the dependent variable; all other variables are controlled

A method describes how an experiment is carried out; a step-by-step procedure.

Command words are words or phrases that indicate what you are expected to do.  They are usually imperative verbs.

When the same person uses the same method and obtains the same / similar results when repeating the experiment.

When a different person uses the same/similar method as another and obtains the same / similar results as that other person.

The process in which a substance's particles separate and spread uniformly throughout the particles of a solvent, resulting in the substance no longer being seen.

Solubility refers to how well a solute is able to dissolve in a solvent to create a solution.

A variable is anything that can change in an investigation.

A result that does not fit an obvious trend.

Data that can only take distinct values or is a category, e.g. shoe size, number of people.

Data that can be a value within a range, e.g. temperature, mass, height, etc.

Chart showing solid columns to present data; usually used when one variable is discrete.

A graph in which two continuous variables are plotted.  It is used to find if a relationship exists between the variables.

A line of best fit is drawn through a set of plotted points on a scatter graph, to best show the trend in the data displayed.

A saturated solution is one in which no more solute can dissolve in the solvent at a given temperature.

Solutions

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