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Group I, II and the Halogens


Group 1: Alkali Metals
Lithium ­ Li, Sodium ­ Na, Potassium ­ K, Rubidium ­ Rb, Caesium ­ Cs.
Group 2:
Beryllium ­ Be, Magnesium ­ Mg, Calcium ­ Ca, Strontium ­ Sr, Barium ­ Ba.
Metallic Bonding: The electrostatic attraction between the cations…

Page 2

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Reaction w/ water:


Group 1 generally happens faster than Group 2.
Reactivity decreases down group
2K(s) + 2H2O(l) 2KOH(aq) + H2(g)
Or Ca(s) + 2H2O(l) Ca(OH)2(aq) + H2(g)


Observations:
Fizzing
Gets smaller and the disappears
Melts into ball (not Li)
Be does not react with steam or water
Mg reacts…

Page 3

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Hydroxides:
Solubility increases down group
Be(OH)2 Mg(OH)2 Ca(OH)2 Sr(OH)2 Ba(OH)2




Sulphates:
Solubility decreases down group


Be(OH)2 Mg(OH)2 Ca(OH)2 Sr(OH)2 Ba(OH)2




Only soluble if it is a big molecule with a small molecule
Stability of Carbonates
Group 1 carbonates are all thermally stable in the Bunsen, except for Li2CO3 which acts…

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Group 2 decomposes to form the oxide, nitrogen dioxide (brown gas) and oxygen:
2Ca (NO3)2 2CaO + 4NO2 + O2
(Measure the time taken for the brown gas to appear or for a glowing splint to relight)
Group 1 decomposes into nitrite and oxygen (except LiNO3 because other group 1…

Page 5

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b) No. of e- shells increase, the shielding increases, and therefore the attraction
decreases
NaCl NaBr NaI
NaCl ----- -----
NaBr Yellow/orange colour -----
Brown colour and/or Brown colour and/or
NaI
black precipitate black precipitate
c) These affects outweigh the increasing nuclear charge.


Oxidising power: F2>Cl2>Br2>I2
Displacement order: F2>Cl2>Br2>I2
Bromine…

Page 6

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Bromide:
NaBr + H2SO4 NaHSO4 + HCl
H2SO4 + 2H+ + 2e- SO2 + 2H2O
2Br- Br2 + 2e-
H2SO4 + 2Br- + 2H+ SO2 + Br2 + 2H2O




Iodide:
NaI + H2SO4 NaHSO4 + HI
H2SO4 + 2H+ + 2e- SO2 + 2H2O
2I- I2 + 2e-
H2SO4 +…

Page 7

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N.b. The HNO3 is to remove any impurities which would react with the AgNO3
Reaction of Cl with NaOH:
At 15C:
o 2NaOH + Cl2 (ox. no. Cl: 0) NaClO (ox. no. Cl: 1) + NaCl (ox. no. Cl: -1) + H2O
o Disproportionation reaction because Cl is oxidised and…

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