topic 6

• What are the properties of the alkali metals?

  Soft, low density, low mpt and bit
• What happens to the reactivity of group one metals as you go down, and why?

  They become more reactive because they have more shells, so the electron is further from the nucleus (there is more shielding), and therefore it can be lost more easily.
• What is the general equation for when a group one metal reacts with water?

  metal + water -> metal hydroxide + hydrogen
• What are group 1 elements also known as?

  alkali metals
• What are group 7 elements also known as?

  Halogens
• What is the colour, state and properties of chlorine at room temperature?

  a green gas (poisonous, fairly reactive)
• What is the colour, state and properties of bromine at room temperature?

  poisonous, red-brown liquid which gives off an orange vapour
• What is the colour, state and properties of iodine at room temperature?

  dark grey crystalline solid which goes off a purple vapour when heated
• What happens to melting points and colour of the halogens as you go down the group?

  - they get darker

  - mpts increase
• What are the properties of the halogens?

  - low boiling points (increase as you go down)

  - poor conductors

  - exist as diatomic molecules
• What happens to the reactivity of the halogens as you go down the group and why?

  They become less reactive, because there is more shielding around the nucleus, so the positive charge is less strong, meaning the one electron needed for a full shell will be less easily gained.
• What happens when a halogen reacts with a metal?

  metal + halogen -> halogen metal (eg sodium +chlorine = sodium chloride)
• What happens when a halogen reacts with hydrogen?

  metal + hydrogen - > sodium

  (eg hydrogen + chlorine = hydrogen chloride)
• How can you use displacement reactions to show the reactivity trend of the halogens?

  1) measure a small amount of a halide salt solution in a test tube

  2)add a few drops of a halogen solution to it and shake gently

  3) if u see a colour change, a reaction happened, if not, there was no reaction

  4) repeat with different combinations of halide salt and halogen solution

  5) work out which was more reactive
• What is group 0/7 also known as?

  noble gases
• What are the properties of the noble gases?

  Odorless, colorless, low reactivity
• What are uses of the noble gases?

  helium - balloon, blimps etc.

  neon - light up signs

  krypton and xenon - photographic flashes

  argon and helium - protect metals that are being welded
• What happens to bpt, mpt and density as you go down group 0?

  they increase
• describe bromine at room temperature

  Bromine is a dense, poisonous, red-brown volatile liquid.
• What would you observe when sodium reacts with water?

  Sodium floats, moves around and fizzes. The metal melts, then disappears and the solution is colourless
• What would you observe when potassium reacts with water?

  a lilac flame, it will more on the surface of the water, it will fizz
• What would you observe when lithium is reacted with water?

  steady fizzing, and it would float
• What is the test for chlorine in a solution?

  Add dampbluelitmus paper, it should turnredthen bleachwhiteif chlorine is present
• Why is an atmosphere of argon used in welding?

  because it is inert due to its full outer shell, so excludes the air from the welding point
• what are the products when an alkali metal reacts with water?

  metal hydroxide and hydrogen gas