Groups of the periodic table

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Group1- Alkali metals

As you go down group 1:

  • Become more reactive because the outer electron is more easily lost because it is further away from the nucleus
  • Have lower melting and boiling points

The alkali metals have low density. The first three float in water

All have one outer electron which makes them very reactive and gives them similar properties

Form Ionic compounds with non-metals

  • They are keen to lose their outer electron to form a 1+ ion
  • They never covalent bond
  • Always form ionic bonds and produce white compounds that dissolve in water to form colourless compounds

When sodium, lithium or potassium are put in water they react vigorously. They float and move around the surface fizzing furiously. They produce hydrogen and potassium even ignites it and causes a squeaky pop. They form hydroxides that dissolve in water to give alkaline solutions

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The Halogens

As you go down group 7:

  • Less reactive because it's harder to gain an electron because the outer shells electron is further from the nucleus
  • Higher melting and boiling point

Halogens are all non-metals with coloured vapours:

  • Fluorine is a very reactive, poisonous yellow gas
  • Chlorine is a fairly reactive, poisonous dark green gas
  • Bromine is a dense, poisonous, red-brown volatile liquid
  • Iodine is a dark grey solid or a purple vapour
  • They all exist as molecules which are a pair of atoms

Halogens form ionic compounds with metals- Form 1- atoms called halides for example NA-CL-

A more reactive halogen can displace a less reactive one from a aqueous solution of its salt. For example chlorine can displace bromine and iodine from an aqueous of its salt, bromine will also displace iodine because of the trend in reactivity.

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Transition metals

Between group 2 and 3 and have these properties:

  • Good conductors of heat and electricity
  • Very dense, strong and shiny
  • Much less reactive than group 1 metals so they don,t react vigorously with water or oxygen
  • Denser, Stronger and harder with group 1 metals and have higher melting points accept mercury
  • Often have more than one ion like iron and chromium which have a 2+ and a 3+ ion which usually form different colour compounds

Compounds are very COLOURFUL:

  • The compounds are colourful due to the transition metal ion they contain. For example Potassium chromate is yellow, Potassium manganate is purple and Copper sulfate is blue.
  • The colours in gemstones like blue sapphires and green emeralds due to transition metals.

Transition metals and their compounds make good catalysts:

  • Iron is the catalyst in the haber process
  • Manganese oxide is a good catalyst for the decomposition of hydrogen peroxide
  • Nickel is useful for turning oils into fats for making margarine

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