5) Group 1

• The elements in Group 1 are known as the alkali metals. They:

  • have one electron in their outermost shell
  • have low melting and boiling points that decrease down the group
  • become more reactive down the group.
• This is because the outer electron gets further away from the influence of the nucleus, so it can be lost more easily.
• Alkali metals are stored under oil because they react very vigorously with oxygen and water, including moisture in the air.
• When alkali metals react with water a metal hydroxide is formed and hydrogen gas is given off.
• Group 1 metals have a low density - lithium, sodium and potassium are less dense than water, so float on top of it.
• When a metal hydroxide (e.g. potassium hydroxide) is dissolved in water, an alkaline solution is produced
• Alkali metals react with non-metals to form ionic compounds.

  When this happens, the metal atom loses one electron to form a metal ion with a positive charge (+1).