4.1.1 group 1

• Group 1 metals are known as Alkali metals. Their outer shell has 1 electron in it, which is usually given away in chemical reactions
• Group 1 metals are usually stored in oil as they are highly reactive with oxygen and water vapour
• Lithium (Li):

  • electron structure (2,1)
  • least reactive of alkali metals
  • burns with crimson flame when reacts with oxygen
  • floats on the surface of water and will release bubbles of hydrogen (it effervesces (gives off bubbles))
• Sodium (Na):

  • electron structure (2,8,1)
  • more reactive than Lithium because outer electron is further away from the nucleus. less strongly attracted to positive nucleus
  • metal floats on the surface of water, which releases heat to melt the sodium. the sodium moves quickly across the surface of water.
  • burns with yellow/orange flame when reacts with oxygen
• Potassium (K):

  • electron structure (2,8,8,1)
  • more reactive than lithium and sodium because its outer electron is less strongly attracted to the nucleus
  • metal floats on surface then burns with lilac flame when it reacts with oxygen
• When group 1 metals react with chlorine, a metal chloride is formed (e.g. sodium chloride) which dissolves in water to give a colourless solution
• When group 1 metals react with water, the metal floats on the surface and melts to create a metal hydroxide (e.g. lithium hydroxide). When they react with water, the energy released is enough to melt the metal
• When group 1 metals react with oxygen, they rapidly turn from a silvery shiny to dull because a metal oxide is produced (e.g. potassium oxide)
• Fill the gaps.

  A) hydroxides

  B) chlorides

  C) oxides

  D) alkali

  
• Reactivity of alkali metals:

  • atoms gain more electron shells as you go down
  • more electron shells = more reactive because there are more electron shells separating the nucleus and the outer electron, which shields the electron from the nuclear charge.
  • the electron is more easily lost, so the atom is more reactive
• The attraction between the positive nucleus and the negative outer electron becomes weaker as you go down the group because the outer electron is further from the nucleus
• As you go down group 1 alkali metals, the reactions become:

  • quicker
  • more vigorous
• Reactions of alkali metals with oxygen.

  Metal + oxygen -> metal oxide + hydrogen

  A) sodium

  B) lithium

  C) potassium