What you are expected to know:
- All substances are made of atoms that have a tiny central nucleus surrounded by electrons.
- The simplest substances contain only one type of atom and are called 'elements'
- Atoms of each element have their own chemical symbol
- The periodic table lists all the known elements in groups with similar chemical properties
- Elements form compounds by combining with other elements: their atoms give, take or share electrons, so they bond together.
- The formula of a substance shows the types of atom it contains and how many have combined together.
- In chemical reactions, the mass of the reactants is always the same as the mass of the products
- Chemical equations are balanced. There is the same number of each type of atom on each side.
- Limestone is used as a building material and to make quicklime, slaked lime, cement and glass.
- Heating metal carbonates produces metal oxides and carbon dioxide gas.
Atoms, elements and compounds
- There are about 100 different elements from which all substances are made
- Elements are listed in the periodic table
- Each element is made of one type of atom.
- Atoms are represented by a chemical symbol, e.g. Na for sodium, O for oxygen.
- Atoms have a tiny nucleus surrounded by electrons. When elements react their atoms join with atoms of other elements
- Atoms form chemical bonds by losing, gaining or sharing a small number…