Metals versus non-metals
The majority of elements are Shiny element that is a good conductor of electricity and heat, and which forms basic oxides.. In the periodic table:
- metals are found to the left and towards the bottom of the periodic table
- Element that is a poor conductor of electricity and heat, and which forms acidic oxides. are found towards the top right of the stepped line
Atomic structure and the periodic table
Elements in group 1 and group 2 are metals. Atoms of group 1 elements have one electron in their outer shell, and atoms of group 2 elements have two electrons in their outer shell.
Some elements in groups 6 and 7, and all in group 0 (also known as group 8) are non-metals. Atoms of group 7 elements have seven electrons in their outer shell, and atoms of group 0 elements, except helium, have eight electrons in their outer shell.
The reactions of elements are related to the number of electrons in their outer shells:
- Atoms of metal elements give away electrons in their reactions to form positive ions. The ions formed have a full outer electron shell, so are very stable.
- Atoms of reactive non-metal elements gain electrons in some of their reactions to form negative ions. The ions formed have a full outer electron shell, so are very stable.
Differences in chemical properties
Most elements are metals. In their chemical reactions, metals atoms lose electrons to form positive ions. For example:
- when magnesium burns in air, each atom loses two electrons to form an Mg2+ ion
- when sodium reacts with chlorine, each sodium atom loses one electron to form a Na+ ion
Elements that do not form positive ions in their chemical reaction are non-metals.
- most metal oxides are Bases react with acids to make salts, and form alkaline solutions if they dissolve in water. Substances or solutions that act as bases are said to be basic.
- most non-metal oxides are Having a pH lower than 7.
Differences in physical properties
Metal and non-metal elements have different A description of the appearance of a substance or how it acts without involving chemical reactions. For example, state, melting point, conductivity, etc.:
- most metals have high melting and boiling points
- most non-metals have low melting and boiling points
The table shows some other differences in physical properties.
| Properties of a typical metal (when solid) | Properties of a typical non-metal (when solid) |
| Good conductor of electricity | Poor conductor of electricity |
| Good conductor of heat | Poor conductor of heat |
| Shiny | Dull |
| High density | Low density |
| Malleable (can be hammered into different shapes) | Brittle (breaks easily) |
| Ductile (can be pulled into wires) | Brittle (breaks easily) |
| Properties of a typical metal (when solid) | Good conductor of electricity |
|---|---|
| Properties of a typical non-metal (when solid) | Poor conductor of electricity |
| Properties of a typical metal (when solid) | Good conductor of heat |
|---|---|
| Properties of a typical non-metal (when solid) | Poor conductor of heat |
| Properties of a typical metal (when solid) | Shiny |
|---|---|
| Properties of a typical non-metal (when solid) | Dull |
| Properties of a typical metal (when solid) | High density |
|---|---|
| Properties of a typical non-metal (when solid) | Low density |
| Properties of a typical metal (when solid) | Malleable (can be hammered into different shapes) |
|---|---|
| Properties of a typical non-metal (when solid) | Brittle (breaks easily) |
| Properties of a typical metal (when solid) | Ductile (can be pulled into wires) |
|---|---|
| Properties of a typical non-metal (when solid) | Brittle (breaks easily) |