represents a substance using element symbols and the number / ratio of atoms of each element in the substance.

is a way of describing a reaction using the chemical names of the reactants and products.

describes a reaction using a symbol equation with coefficients, which ensure there are equal numbers of atoms of each element on both sides of the symbol equation.

is the number placed in front of a chemical formula to balance an equation; it multiplies all the atoms in the formula and shows the ratio of substances in a reaction.

Conservation of mass and balanced symbol equations

Science

Characteristics of chemical reactions

Chemical reactions: oxidation

Chemical reactions: combustion

Chemical reactions: decomposition

Chemical reactions: precipitation

In the Acids and Bases unit, pupils will build on their understanding of chemical reactions to learn about the properties of acids, bases, alkalis, and the neutralisation reaction.

In the Atoms, Elements and Compounds unit, pupils learned about atoms, elements, and compounds and how particles reorganise in a chemical reaction.

This unit covers the conservation of mass in changes of state and chemical reactions, including atom rearrangement. It also focuses on representing reactions with formulae and equations, exploring combustion, decomposition, and displacement, and distinguishing chemical from physical changes.

Understanding chemical reactions

What does the arrow in a chemical equation represent?

The mass of the reactants is greater than the mass of the products.

The mass of the reactants is less than the mass of the products.

The mass of the reactants is equal to the mass of the products.

The mass of the reactants can be greater or less than the mass of the products.

Which of the following statements about the mass of reactants and products in a chemical reaction is correct?

A way of describing a reaction using symbols.

A way of describing a reaction using chemical names of reactants and products.

To show that matter is created or destroyed.

To correctly represent the conservation of mass.

A {{}} represents a substance using element symbols and the number/ratio of atoms of each element in the substance.

To balance a chemical equation, you need to change the {{}} in front of the chemical formulas to ensure there are equal numbers of atoms of each element on both sides of the equation.

Two or more atoms chemically bonded together.

In a chemical reaction, the substances formed are called {{}}.

What happens to atoms during a chemical reaction?

What is the chemical formula for carbon dioxide?

A chemical symbol {{}} is a representation of a chemical reaction using the symbols of the elements involved.

Starter Quiz

What is a molecule?