Science notes – METALS & NON-METALS

Group first 20 elements of the periodic table into metals and non-metals

Properties of metals

Metals are generally shiny, malleable elements that conduct heat and electricity well. Most are solid at room temperature.

In chemical reactions metals tend to form positive ions.

Differences between metals and non-metals

Metals are generally shiny, malleable elements that conduct heat and electricity well. Most are solid at room temperature. In reactions metals tend to form positive ions.

Non-metallic elements have more varied properties than metals. They are poor conductors of heat and electricity and in reactions non-metals commonly form negative ions.

Composition of some common alloys and their uses

Steel ← iron and carbon
Brass ← copper and zinc
Bronze ← copper and tin

Uses of alloys: Alloys are used in making currency coins, 'silver' cups, brass bowls, sardine tins, spoons, airplanes, cars, wrist watches.

Define corrosion. Effects of corrosion

Corrosion of metals is the wearing away of the metal by the action of chemicals.

Effects of corrosion

Acid rain corrodes the paint work of buildings.

Old dry cell batteries corrode the metal container of electric torches.

Skin toning creams corrode the faces and bodies of users.

Process of rusting: the reaction of a metal with atmospheric oxygen in the presence of moisture.

Effects of rusting e.g. metallic iron loses its strength and structure.

NOTE: Rusting occurs only in iron.

Ways of preventing rusting

Rusting can be prevented by:

1. Oiling
2. Greasing
3. Painting
4. Zinc or Chromium coating

Explain how oiling prevents rusting

The oil forms a barrier between the metal iron and atmospheric oxygen and moisture thus prevents rusting.