Group 1 (I) – The alkali metals
Group 1 elements have similar physical and chemical properties because they all have one electron in the outer shell of their atoms.
- low density. The first three – lithium, sodium and potassium – are less dense than water and therefore float on water.
- very soft. They are easily cut with a knife.
- shiny when first cut, but tarnish rapidly in air.
- low melting points. The melting points decrease as the atoms get bigger going down the group.