Basic chemistry help for students and teachers


Interactive Chemistry Worksheets for Students


Periodic table

Naming compounds

Basic formula

Simple compounds

Ionic compounds 1

Ionic compounds 2

Chemical suffixes

Old chemical names

Hydrocarbons - Alkanes

Alkanes, alkenes & alkynes

Alkanols to alkanoic acids


Common compounds

Common formula quiz

Acids, bases and salts

Covalent compounds

Printable worksheets



Practice balancing chemical equations. Worksheets with answers

Practice balancing 100's of chemical equations from simple to advanced. Each chemical equation worksheet comes with answers and can be downloaded as a pdf file.

Chemistry worksheets for download

Identification of salts from a variety of acid reactions


What happens in a chemical reaction?

Chemical reactions are like a ‘dance’. The people starting the dance are called reactants. The number of people on the dance floor remains the same. During the dance people change partners and form new groups called products. This is what happens in a chemical reaction. Atoms swap with one another and produce new chemicals.

Old chemicals(reactants) rearrange to produce new chemicals(products)

Reactants → Products

The arrow means 'produces'

In a chemical reaction atoms are rearranged as old chemical bonds are broken and new chemical bonds are formed.The 'law of conservation of mass' is supported as the weight doesn’t change between the mass of the reactants and the mass of the products.


How to balance a chemical equation

In balancing chemical equations you need to remember to three important points.

  1. You do not change the chemical formula of a substance to balance an equation.
  2. An equation is balanced by writing whole numbers before a chemical symbol or formula.
  3. The type and number of atoms must balance on both sides of the chemical equation.


Example of how to balance a chemical equation

Write a balanced chemical equation of hydrogen combining with oxygen to produce water.

Hydrogen + Oxygen →Water

H2 + O2 → H2O

The type and number of atoms must be the same on both sides of the equation.

Check the number of atoms for each element.

Element Reactants Products
H 2 2
O 2 1

An oxygen atom cannot disappear in the reaction.

H2 + O2 → H2O (one oxygen atom short)

A helpful hint is to look for an odd number of elements in the product side of the reaction and double it.

The oxygen in H2O is an odd number so it is doubled. H2 + O22H2O

Check the number of atoms for each element.

Element Reactants Products
H 2 4
O 2 2

The oxygen is now balanced, however now we don't have enough hydrogen atoms. Since the hydrogen atoms come in pairs we need 2 pairs to make 4.

Check the number of atoms for each element.

Element Reactants Products
H 4 4
O 2 2

2H2 + O22H2O

The chemical equation is now balanced!