AS CHEMISTRY UNIT 2 - PIGUY
GROUPS 1&2
>>REVISION>>
FLAME TESTS
Li
RED
Na
ORANGE
K
LILAC
Rb
RED-VIOLET
Cs
BLUE
electron is promoted to higher
energy level by heat; when it
drops down, energy is given off
as light
Mg
Ca
Sr
Ba
WHITE
BRICK RED
CRIMSON RED
APPLE COX GREEN
Mg(s) + O2 (g)
2MgO(s)
Ba & Sr also form peroxides (e.g. BaO2)
ɣ
e-
GROUP II REACTIONS
CaCl2(s) +
2H2O (l)
Mg doesn’t react with H2O (l)
Be / BeO doesn’t react with
either H2O (l) or (g)
+ Cl2 (aq)
CaCl2(s)
+ H2O(l)
+ dil. 2HCl
Ca(s)
+ 2H2O (l)
+ dil. 2HCl
Ca(OH)2 (s)
+ H2 (g)
+ H2O (g)
+ H2O (l)
CaO(s) + H2 (g)
GROUP I & II
TRENDS
down the group the solubility of
sulphates decrease
hydroxides increase
T H E R M A L S TA B I L I T Y
C-O BOND
EASIER TO
BREAK
O
C
O
down the group the thermal
stability of nitrates and
carbonates increase
Smaller positive ion means
greater charge density
Increase in ability to pull the O,
weakening the C-O bond,
so less thermal energy required
O-
M g 2+
OO
C
O
B a 2+
AS CHEMISTRY UNIT 2 - PIGUY
GROUP 7
>>REVISION>>
PROPERTIES OF
GROUP VII ELEMENTS
GOOD OXIDISING AGENTS
I2 > Br2 > Cl2
Cl2
in
solution
Br2
in
solution
I2
in
solution
PROPERTIES
OF HALIDES
GOOD REDUCING AGENTS
C l -> B r - > I - S O D I S P L A C E M E N T O C C U R S
2KBr + Cl2 (aq)
2KCl + Br2 (aq)
PA L E G R E E N G A S
PA L E G R E E N S O L U T I O N
DARK RED LIQUID
ORANGE SOLUTION
GREY SOLID
with
AgNO
AgCl
colour
of ppt.
white cream yellow
dissolves
in
PURPLE SOLUTION
* I O D I N E O N LY D I S S O LV E S I N N O N POLAR SOLUTIONS, NOT WATER
2AgCl (s)
dil.
NH
AgBr
conc.
NH
sunlight
AgI
-
2Ag + Cl2
GROUP VII ELEMENT REACTIONS
halogens act as oxidising agents e.g.
2FeCl3
2Fe + 3Cl2 (aq)
DOWN THE GROUP THEIR LESS GOOD AT OXIDISING
SO IODINE GOES:
Fe + I2
FeI2
DISPROPORTIONATION
2NaOH (aq) + Cl2 (aq)
hot
NaCl + NaClO + H2O
6NaOH(aq) + 3Cl2 (aq)
cold
5NaCl + NaClO3 + 3H2O
GROUP VII IONS REACTIONS
halides act as reducing agents e.g.
H 2S O 4 R E D O X ( D O E S N ’ T W O R K F O R C l -)
2BrH2SO4 + 2H+ + 2eH2SO4 + 8H+ + 8e-
Br2 + 2eSO2 + 2H2O
H2S + 4H2O
EGG SMELL
* O N LY F O R
IODIDE
HYDROGEN HALIDE REACTIONS
HCl (g) + NH3 (aq)
NH4Cl (aq)
HCl (g)+ H2O (l)
H3O+ + Cl-
WHITE SMOKE
YOU’RE
DONE WITH
INORGANIC
CHEMISTRY
REVISION!