Properties of Metals and Non-metals: Quick Revision

A brief note on Properties of Metals and Non-metals. Read it before a test. Try each question at the end before you open its answer.

Metals and non-metals

The exceptions

• Metals: mercury is a liquid; sodium and potassium are soft and float; lead and mercury conduct heat poorly; gallium melts in the hand.
• Non-metals: graphite conducts; iodine is shiny; diamond is the hardest natural substance; bromine is a liquid.
• Metalloids, such as silicon and germanium, have properties of both.

Alloys

Brass: copper and zinc. Bronze: copper and tin. Solder: lead and tin. Steel: iron and carbon. Stainless steel: iron, chromium and nickel. $k$ carat gold is $\dfrac{k}{24}$ gold.

A worked example

A $7.5\ \text{g}$ coin is cupronickel: $75\ \%$ copper and $25\ \%$ nickel. Find the mass of each metal.

1. Copper. $7.5\ \text{g} \times 0.75 = 5.625\ \text{g}$.
2. Nickel. $7.5\ \text{g} \times 0.25 = 1.875\ \text{g}$.
3. Check. $5.625\ \text{g} + 1.875\ \text{g} = 7.5\ \text{g}$.

Practice with new numbers

A program to try

The program works out the worked example.

Mistakes to avoid

• Judging by one property. Iodine shines and graphite conducts, yet both are non-metals.
• Calling an alloy a compound. It is a mixture, and its recipe can vary.
• Mixing up brass and bronze. Brass has zinc; bronze has tin.
• Thinking 24 carat gold is best for jewellery. It is too soft.

Check yourself

1. Which non-metal is shiny?

2. Why can sodium be cut with a knife?

3. Which alloy is used for bells and statues?

4. Name a metalloid that is used to make computer chips.