Groups in the periodic table

group 0

→ noble gases

• as you go down the density increases

• helium:

  1. inert as they have a full outer shells of electrons

  2. used for balloons as it is less dense then air, and is unreactive

• they are all colourless, low melting + boiling point, exists as a single atom

• neon

  1. used in illuminated signs as it has a orange-red light when electricity passes through it

group 1

→ alkali metals

• as you go down the reactivity increases, the group the outer electron becomes easier to lose as it’s not as strongly attracted to the nucleus

• they are all soft and very rectivity

• they are all easily cut and are shiny on inside, and dull (layer of oxide) on the outside

• stored in oil to prvent reaction with air

• low melting + boiling points

→ reaction with H2O → metel hydroxides (alkalis)

→ group 1 metel + water → metal hydroxide + hydrogen

• observation → reactivity increases

  1. Li - floats, fizzing, moves across aurface of the water

  2. Na - float, fizzing, melts into a abll, moves quickly

  3. K - float, fizzing, melts into a ball, ignites with a lilac flame, moves quickly

group 7

→ halogens

• Cl → green gas, Br → orange/brown liquid, I → grey solid

• as you down the density increases, and the melting + boiling point increases

• chemical test for chlorine: bleaches damp blue litmus paper white

redox

→ oxidation + reduction happening at the same time

• Oxidation Is the loss of Electrons

• Reduction Is the gain of Electrons

reactions with metels

→ halogens react with metals to make ionic compound (halides)

• e.g. 2Na (s) + Cl2 (g) → 2NaCl (s)

reactions with non-metals

→ react with hydrogen to make hydrogen halides

• e.g. H2 = Cl2 → 2HCl

hydrogen halides dissolves in water to make acids

• HCl (g) → *+H2O* → 2HCl (aq)

(redox) displacment reaction

→ a more reactive halgon will displace a less reactive halogen from a aquous solution → a colour change is seen

• Cl2 + 2KBr → 2KCl + Br2

• Cl2 + 2Kl → 2KCl + I2

exploring reactivity

→ as you go down the group, the electron gained in less attracted to nucleus → it’s further away

• F + e- → F-