Metals versus non-metals

The majority of elements are metals. In the periodic table:

  • metals are found to the left and towards the bottom of the periodic table
  • non-metals are found towards the top right of the stepped line
Artwork of the Edexcel periodic table minus the numbers in the boxesMetals are on the left of the periodic table, and non-metals are on the right

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
How a sodium atom becomes a sodium ion when it loses an electronA sodium atom, Na, forms a Na+ ion by losing an electron

Elements that do not form positive ions in their chemical reaction are non-metals.

  • most metal oxides are basic
  • most non-metal oxides are acidic

Differences in physical properties

Metal and non-metal elements have different physical properties:

  • 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 heatPoor conductor of heat
ShinyDull
High densityLow density
Malleable (can be hammered into different shapes)Brittle (breaks easily)
Ductile (can be pulled into wires)Brittle (breaks easily)

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