Page 58 - 新思维科学学生用书7 样章

2.6 Compounds and formulae

Questions

1 Describe two ways in which sodium chloride is different from sodium.
2 Describe two ways in which sodium chloride is different from chlorine.

Naming compounds

Each compound has a chemical name. The chemical name usually tells you the elements that the
compound is made from.

There are important rules to remember when naming compounds.
• If the compound contains a metal, then the name of the metal comes first in the name of the

compound.
• If the compound contains a non-metal, the name of the non-metal is usually changed. For
example, the compound made from sodium (a metal) and chlorine (a non-metal) is not sodium
chlorine, but sodium chloride.

• When two elements form a compound, the name often ends in ‘ide’.

Questions

3 Which two elements are combined in sodium chloride?
4 Which two elements are combined in hydrogen sulfide?
5 Which two elements are combined in magnesium oxide?
6 A student wrote this name for a compound made of calcium and sulfur:

sulfur calcium
What is wrong with this name? Write the correct name for the compound.

Some compounds contain two different

elements, plus a third element – oxygen. These
compounds often have names ending with
‘ate’. For example, a compound of calcium,
carbon and oxygen is called calcium carbonate.

These are crystals of copper sulfate. Copper sulfate is a
compound made up of copper, sulfur and oxygen.

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