1. Physical properties of metals ad non-metals
| Physical properties | Metals | Non-metals |
| Melting and boiling points | Most metals have high melting and boiling points (except alkali metals). Metals are usually solids (except for mercury) at room temperature. | Non-metals always have low melting and boiling points. They are solids and gases at room temperature (except for bromine which is a liquid). |
| Electrical conductivity | All metals are good conductors of electricity. | Non-metals are poor conductors of electricity (except for graphite). They tend to be insulators. |
| Thermal conductivity | Metals are good conductors of heat. | Non-metals are generally poor thermal conductors (except diamond, which conducts heat strongly). |
| Malleability and ductility | The shape of a piece of metal can be changed by hammering (they are malleable). They can also be pulled out into wires (they are ductile). | Non-metals are not malleable; they are brittle and weak easily when hit. |
| Strength and hardness | Metals are usually strong and dense. When a force is applied, they are hard and do not shatter (they are not brittle). | Most non-metals are softer than metals (but diamond is very hard). Their densities are often low. |
| Ability to produce a sound | Metals usually make a ringing sound when struck (they are sonorous). | Non-metals are not sonorous. |
| Colour and appearance | Metals are grey in colour (except god and copper). They can be polished. | Non-metals vary in colour. They often have a dull surface when solid. |
2. Chemical properties of metals
(1) Reactions of metals with air/oxygen
Many metals react directly with oxygen to form oxides. Magnesium, for example, burns brightly in air or oxygen to form a white powder of magnesium oxide.
magnesium + oxygen → magnesium oxide
2Mg + O2 → 2MgO
(2) Reactions of metals with water/steam
Reactive metals such as potassium, sodium and calcium all react with cold water to produce the metal hydroxide and hydrogen gas.
metal + water → metal hydroxide + hydrogen
2Na + 2H2O → 2NaOH + H2
Ca + 2H2O → Ca(OH)2 + H2
Magnesium only reacts very slowly in cold water. However, a much more vigorous reaction takes place if steam is passed over heated magnesium. The magnesium glows brightly to form hydrogen and magnesium oxide. The hydrogen given off an e burnt when lit with a splint.
magnesium + steam → magnesium oxide + hydrogen
Mg + H2O → MgO + H2
(3) Reactions of metals with dilute acids
Moderately reactive metals such as magnesium, zinc or iron can be reacted safely with dilute acid to produce hydrogen gas.
iron + hydrochloric acid → iron(II) chloride + hydrogen
Fe + 2HCl → FeCl2 + H2
zinc + hydrochloric acid → zinc chloride + hydrogen
Zn + 2HCl → ZnCl2 + H2
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