CC13: Groups in the periodic table

• What are the physical properties of group 1 (alkali metals)?


  • are soft (they can be cut with a knife)
  • have relatively low melting points
  • low densities the first three (lithium, sodium and potassium) to float on water.
  • melting point decreases down the group
• What are the main physical properties of alkali metals?

  Soft enough to cut with a knife, low melting points and low density
• what are the main chemical properties of alkali metals?

  very reactive and form compounds with non metals
• what is the reaction of lithium and water like?

  bubbles fiercely on the surface
• what is the reaction of sodium and water like?

  melts into a ball and fizzes around the surface
• what is the reaction between potassium and water like?

  bursts into flames and flies about the surface
• why does the reactivity decrease down the alkali metals or group 1?

  the atoms become larger down the group because each element has an additional full shell of electrons and since the distance between the positively charged nucleus and the negatively charged electron increases so the forces of attraction are lower and the nucleus is more easily lost.
• what is the structure of the halogens?

  diatomic molecules with two atoms held together by a single covalent bond
• what are the properties of the halogens or group 7?

  they get darker as you go down the group, they are non metallic so are poor conductors of heat and electricity, they are all toxic and corrosive
• what is the appearance of chlorine at room temperature?

  pale green gas
• what is the appearance of bromine at room temperature?

  brown/ red liquid
• what is the appearance of iodine at room temperature?

  grey solid
• what is the test for chlorine gas?


  place damp blue litmus paper in the gas and if it is chlorine gas the paper will turn red and then white
• how do certain properties change depending or their place in the group?

  • low melting and boiling points that increase down the group
  • densities increase down the group
• what is the relative reactivity for halogens?

  forces of attraction become less so ions do not form as easily so the reactivity decreases
• how do displacement reactions work?

  AB + C ——> AC + B

  • ionic compound but C is more reactive than B so AC form a New Ionic compound
  • B has been displaced by C
  • you can predict that the more reactive element will be the one that was on its own but formed a New Ionic compound
• How are displacement reactions examples of redox reactions?

  Displacement reactions are always redox, redox is a reaction where reduction (gaining electrons) and oxidation (loosing electrons) happen together.
• how do you remember what oxidation and reduction mean ?

  OIL RIG

  oxidation is loosing

  reduction is gaining
• Why are noble gases chemically inert?

  • their atoms have full outer shells of electrons so they have no tendency to loose, gain or share electrons
• how are the uses of noble gases linked to their properties?

  helium: lifting gas because it is less dense than air and non flammable so it has a low density and is inert

  argon, krypton and xenon: filling gas, inertness stops the metal filament burning away but keeps it hot enough to glow

  argon: shield gas, denser than air so it keeps the air away form the metal and its inertness means the metal doe snot oxidise