topic 4 Flashcards
what happens to the atomic radius down a group and why
increases
extra shells added
what do all group 2 metals have at the end of electronic configuration
S2
what happens to ionisation energy down group 2 and why
decreases
more shielding
increase in protons overriden by sheilding
how do G2 react with water
form bases
metal hydroxides
Sr + H2O –> Sr(OH)2 + H2
what happens to reactivity with water down group 2 and why
increases
atoms get larger
more shielding
how does Mg react with cold water and steam
slowly with cold water
more vigorously with steam producing magnesium oxide
how do G2 react with oxygen using Mg as example
metal oxides
2Mg + O2 –> “MgO
Mg oxidised
O reduced
how does G2 react with chlorine using Mg as example
metal chlorides
Mg + Cl2 –> MgCl2
Mg oxidised
Cl2 reduced
how do G2 oxides react with water
form bases
SrO + H2O –> Sr(OH)2
more alkaline down group and hydroxides become more soluble
how do group 2 oxides react with HCl using calcium oxides as example
neuralisation
CaO+ 2HCl –> CaCl2 + H20
how do group 2 hydroxides react with HCl using calcium hydroxide as example
Ca(OH)2 + 2HCl –> CaCl2 + 2H2O
neutralisation
what happens to the solubility of G2 sulfates and G2 hydroxides down the group
sulfates SO4 2-
less soluble
hydroxides OH-
more soluble
how do G2 carbonates decompose using calcium carbonates as example
metal oxides + carbon dioxide
CaCO3 –> CaO + CO2
how do G2 nitrates decompose using calcium nitrate as an example
metal oxides + nitrogen dioxide + oxygen
2Ca(NO3)2 –> CaO + 4NO2 + O2
what is the trend in thermal stability down group 2 and why
more thermally stable down
lower charge density so less distortion
are G1 compounds more or less thermally stable than G2 and why
more
+1 charge so less distortion
do G1 carbonates decompose
no thermally stable except lithium
Li2CO3 –> Li2O + NO2 + O2
how do G1 nitrates decompose with lithium nitrate and potassium nitrate as examples
for nitrites and oxygen
LiNO3 –> Li2O + NO2 + O2
2KNO3 –> 2KNO2 + O2
how to measure thermal stability of nitrates
NO3 -
how long it takes for specific amount of O2
gas syringe or relight glowing splint
length of time for specific amount of NO2
brown toxic gas
how to measure thermal stability of carbonates
CO3 2-
length of time for specific volume of CO2
turns lime water cloudy
gas syringe
how to carry out a flame test
- dip nichrome wire in conc. hydrochloric acid
- dip into sample
- place loop into blue busen flame and observe colour change
why do you get different colours on the flame tests
electrons move to higher energy levels as they absorb energy from the flames
when they drop back down light is released
difference in energt levels determines wavelength of light energy released
what are the flame colours of lithium, sodium, potassium, rubidium, caesium, calcium, strontium, barium
lithium - crimson
sodium - yellow orange
potassium - lilac
rubidium - red
ceasium - blue
calciul - brick red
strontium - crimson
barium - green
what happens to the boiling points of G7 down and why
increases
london forces increase
size increases
Mr increases
what happens to the electronegativity down G7 and why
decreases down
larger atoms
distance from nucleus to bonding electrons increases
more sheilding
what happens when potassium chloride solution reacts with chloride water, bromine water and iodine solution with colours of organic and aq
chloride water - no reaction
aq - colourless
org - colourless
bromine water - no reaction
aq - yellow
org - orange
iodine solution - no reaction
aq - brown
org - purple
what happens when potassium bromide solution reacts with chloride water, bromine water and iodine solution with colours of organic and aq
chloride water -
Cl2 + 2Br- –> 2Cl- + Br2
aq - yellow
org - orange
bromine water - no reaction
aq - yellow
org - orange
iodine solution - no reaction
aq - brown
org - purple
what happens when potassium iodide solution reacts with chloride water, bromine water and iodine solution with colours of organic and aq
chlorine water -
Cl2 + 2I- –> 2Cl- + I2
aq - brown
org - purple
bromine water
Br2 + 2I- –> 2Br- + I2
aq - brown
org - purple
iodine solution - no reaction
aq - brown
org - purple
how does G7 react with group 1 and G2 with Cl2 as the example with Mg and Li
forms metal halides
Mg + Cl2 –> MgCl2
2Li + Cl2 –> 2LiCl
what is the oxidation state of chloride/bromide
Cl-/Br-
-1
what is the oxidation state of chlorine/bromine
Cl/Br
0
what is the oxidation state of chlorate(I)
ClO-
+1
what is the oxidation state of bromate(I)
BrO-
+1
what is the oxidation state of bromate (III)
BrO2 -
+3
what is oxidation state of iodate (V)
IO3 -
+5
what is the oxidation state of iodate (VII)
IO4 -
+7
how do halogens react with cold alkalis
X2 + 2NaOH –> NaOX + NaX + H20
0 –> +1 and -1
how do halogens react with hot alkalis
3X2 + 6NaOH –> NaXO3 + 5NaX + 3H2O
0–>+5 and -1
how is bleach made
chlorine + sodium hydroxide –> sodium chlorate (I)
Cl2 (g) + 2NaOH (aq) –> NaClO (aq) +NaCl (aq) +H2O (l)
disproportionation reaction
what is bleach used for
treating water
bleaching paper and fabrics
cleaning agents
what happens during water sterilisation
produces chlorate (I) ions which kill bacteria
H2O + Cl2 –><– HCl + HClO
HClO + H2O –><– ClO- + H3O+
what happens to the reducing powerof halide ions down the group and why
increases down
increased ionic radius
more sheilding
decreased attractive force
outer electrons more readily lost
how to test the reducing power of the halide ions
reaction with sulfuric acid
reaction with silver nitrate solution
how does Cl- react with surfuric acid
H2SO4 + NaCl –> NaHSO4 + HCl
produces white misty fumes
how does Br- react with sulfuric acid
- H2SO2 + NaBr –> NaHSO4 + HBr
white misty fumes - 2Br- –> Br2 +2e-
orange vapour
H2SO4 + 2H+ +2e- –> SO2 + 2H2O
= H2SO4 + 2H+ + 2Br- –> Br2 + SO2 + 2H2O
how does I- react with sulfuric acids
- H2SO4 + NaI –> NaHSO4 + HI
white misty fumes - 2I- –> I2 + 2e-
organge vapour
H2SO4 + 2H+ + 2e- –> SO2 + 2H2O
= H2SO4 + 2H+ + 2I- –> I2 + SO2 + 2H2O - 6I- –> 3I2 + 6e-
H2SO4 + 6H+ + 6e- –> S + 4H2O
yellow solid S
= H2SO4 + 6H+ + 6I- –> 3I2 + S + 4H2O
- 6I- –> 3I2 + 6e-
- 8I- –> 4I2 + 8e-
H2SO4 + 8H+ + 8e- –> H2S + 4H20
rotton egg smell
= H2SO4 + 8H+ + 8I- –> 4I2 + H2S + 4H2O
what observation happens when hydrogen halides react with water in the air
form white misty fumes
what observation happens when hydrogen halides react with amomonia gas
white fumes of ammonium halides
what happens when iodide ions react with silver nitrate then ammounia
add dilute nirtic acid then silver nitrate
yellow precipitate
insoluble in all ammonia
what happens when you react bromide ions with silver nitrate
add dilute nitric acid the silver nitrate
cream precipitate
dissolves in conc. ammonia
what happens when you react silver nitare with chloride ions
add dilute nitric acid the silver nitrate
white precipitate
dissolves in dilute ammonia
how to test for carbonates
HCl reacts to make CO2 gas which turns limewater cloudy
how to test for sulfates
add HCl to remove carbonates
add barium chloride
white precipitate
how to test for ammonium compounds
add NaOH and heat
damp red litmus paper turns blue
how to test for hydroxides
turn red litmus paper blue
