What are materials made of?
       4. Elements and compounds
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Everyday materials
Most materials around us are mixtures of compounds. Look at the labels of processed foods and drinks, cosmetics, medicines or clothes. You will find a long list of different compounds. It is actually quite unusual to find an example of a single compound that has not had another one added to it.
Deodorant ingredients
Picture 4.3 The mixture of ingredients in a deodorant.

How common are elements?
Elements are much less common than compounds in the materials around us. This is because they tend to combine with each other to form compounds.

Silver and gold are two elements that we do see. This is because they have less tendency than most other elements to combine.

The air we breathe is made up of a mixture of gases. Most of it is made up of two elements: nitrogen and oxygen.

How many elements are there all together?
Altogether, more than 110 elements have been discovered. Scientists took many years to identify them all. This was because most of them were found combined with other elements as compounds. It was difficult to distinguish between the many compounds in a complex mixture of compounds. And then it was difficult to un-combine the elements in a single compound.
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Question 17
Look at the table below. It describes some elements that are found in the world around us. In each case, work out what the element is and type its name into the box.

Use only small letters and make sure you spell the answers correctly.

Description name (use only small letters)
An unreactive gas that makes up about 78% of the Earth's atmosphere.
A gas that is essential for us to be able to breathe.
A reddish metal that is a good electrical conductor and is found in most cables and electric motors.
A black element that makes up most of coal.
A metal that was used a lot in large scale construction in the 19th century. It needs protecting from the weather because it rusts easily.