The Periodic Table

• Group  0 elements are called NOBLE GASES.

• They include:They are INERT - they don't react with other elements.
  • Helium
  • Neon
  • Argon
  • Krypton
  • Xenon
  • Radon

• This is because they have a full outer shell of electrons already, so they don't need to lose or gain electrons to get a full outer shell.

• Group 1 elements are called ALKALI METALS

• They are:Their reactivity increases as you go down the group.
  • Lithium
  • Sodium
  • Potassium
  • Rubidium
  • Caesium
  • Francium

• This is because as you go down, the outermost electron is in a shell further away from the nucleus.
  

• So the attraction between the nucleus and the electron decreases.

Lithium

• Effervascence takes place.
• Moves slowly around the surface of the water till it disappears.

Sodium

• Lots of effervascence
• Moves quickly round the surface of the water

Potassium

• Reacts vigorously
• Burns with a lilac flame
• Moves very quickly over the water

• Group 7 elements are called HALOGENS.

• They are:As the atomic number of halogens increase, the elements have a darker colour and higher boiling point.
  • Fluorine
  • Chlorine
  • Bromine
  • Iodine
  • Astatine

• The higher up an element is, the more reactive it is.

• This is because the outer shell with the missing electron is nearer to the nucleus, so the pull from the positive nucleus is greater.

• A displacement reaction is where a more reactive element displaces a less reactive element from a compound.

• Example:
  • If you add chlorine water to potassium iodide solution the chlorine will react with the potassium in the potassium iodide to form potassium chloride.
  • The iodine is displaced from the salt.

• Displacement reaction involve the transfer of electrons.

Cl2(aq)   +   2I- (aq)   =   2CL-(aq)   +   2KCl (aq)

• A loss of electrons is called oxidation.
• A gain in electrons is called reduction
• Reactions where reduction and oxidation happen at the same time are called redox reactions.