Basic Chemistry/Compounds

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Compounds contain two or more elements joined up. When atoms join together, they form molecules. To make a compound, you need to join atoms from different elements. The join is called a chemical bond.

Chemical reactions

In a chemical reaction, two or more chemicals (called the reactants) combine together to make one or more new substances (called the products). The new compounds produced from the chemical reaction are always completely different from the original reactants.

Naming compounds

When TWO ELEMENTS combine, the ending is -IDE

• The compound NaCl is made up of the elements sodium and chlorine, so it's name is sodium chloride.
• The compound MgO is made up of the elements magnesium and oxygen, so it's name is magnesium oxide.

When MORE THAN TWO elements combine and one of them is OXYGEN, the ending is -ATE

• The compound CuSO₄ is made up of 1 copper, 1 sulfur and 4 oxygens, so it's name is copper sulfate.
• The compound CaCO₃ is made up of 1 calcium, 1 carbon and 3 oxygens, so it's name is calcium carbonate.

When TWO IDENTICAL elements combine, the name DOESN'T CHANGE

• H₂ = hydrogen
• N₂ = nitrogen
• O₂ = oxygen
• F₂ = fluorine
• Cl₂ = chlorine