Unit 2

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State & Explain trend in atomic radius in period 3
Decreases across period. No of protons increases, so e- pulled closer to nucleus. No extra shielding since e- added onto same shell.
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State trend in melting points in period 3
Generally increase from Na to Si, and generally decrease from Si to Ar.
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Explain trend of Na, Mg, Al m.p.
Mp increase across period since metal-metal bonds get stronger, as increasing no of protons and delocalised electrons in addition to decreasing radius.
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State and explain Si mp
High mp. Since macromolecular (tetrahedral structure) has many storng covalent bonds, linking all its atoms together.
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Explain behaviour of P4, S8, and Cl2
Simple molecular substances, depend on strenght of VdW forces. Easily overcome so these elements have low mp/bp. S8 biggest molecule so higher Mp than P4/Cl2. Ar has very low mp since it exists as single atoms (so weak vdw)
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State & Explain IE1 trends across group 3
Increases. Decreasing atomic radius, increasing nuclear charge, and no shielding difference.
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State and explain group 2 atomic radius trend
Gets larger, since extra e- shells are added as you go down the group.
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State & Explain IE1 trend down group 2
Decreases down group. Each element down gorup 2 has extra shell compared to one above. Extra inner shells shield outer e- from attraction of nucleus. Increasing atomic radius. Therefore lower IE sicne easier to remove e-.
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Reactivity down group 2
Essentially inversely proportional to IE1. As it becomes easier to remove e-, it becomes more reactive. Therefore reactivity increases down group as IE1 decreases down the group.
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Melting point down group 2
Generally decreases down group. As you go down, metal ions get bigger but no of delocalised e- per atom doesnt change. Larget atomic radius => delocalised e- farther away from nucleus. Hence lower energy to break bonds, and mp goes down.
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Blip in melting point down group 2
Mg since arrangement of metallic ions changes.
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Ionic equation of group 2 metal.
M --> M(2+) + 2e-
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Reaction group 2 with water
M + 2H2O --> M(OH)2 + H2 -- REACT MORE READILY DOWN GROUP
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OH(-) Solubility increases up/down group
down
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SO4(2-) Solubility increases up/down group
up
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Use of barium sulfate
barium meals
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Explain steps of titanium extraction
(1) TiO2 converted to TiCl4 by reacting with C in stream of Cl2(g). (2) TiCl4 then purified by frac. distillation, before being reduced by Mg in furnace ~1000*C.
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Reaction of Mg with TiCl4
TiCl4(g) + 2Mg(l) ---> Ti(s) + 2MgCl(l)
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Removing SO2 from flue gas steps
(1) CaCO/CaCO3 mixed with H2O to form slurry. (2) Slurry sprayed on flue gases. (3) SO2 reacts with slurry and produces solid waste product Calcium Sulfate.
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Slurry of CaCO reaction
CaCO + 2H2O + SO2 ---> CaSO3 + 2H2O
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Slurry of CaCO3 reaction
CaCO3 + 2H2O + SO2 ---> CaSO3 + 2H2O + CO2
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Use of Ca(OH)2
agriculture to neutralise acidic soils
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Mg(OH)2
ingestion tablet as antacid.
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Halogens bp trend
Increases down group (as increasing vdw as size and mr increases)
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Halogen e-negativity trend
decrease down group since atoms become larger and e- are more shielded
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KCl reaction outcome with Cl2, Br2, I2
no reaction no reaction no reaction
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KBr reaction outcome with Cl2, Br2, I2
br2 formed no reaction no reaction
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KI reaction outcome with Cl2, Br2, I2
I2 formed I2 formed no reaction
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How to make bleach
Cl2(g) mixed with cold dilute NaOH at room temp (298K)
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Bleach equation
2NaOH + Cl2 --> NaClO + NaCl + H2O
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type of reaction forming bleach
disproportionation
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Cl2 reaction with H2O
Cl2 + H2O 2H+ + Cl- + ClO- (also disporportionation)
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Cl2 reaction with H2O with sunlight
Cl2 + H2O 2H+ +2Cl- + 1/2 O2
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Use of chlorate ions
kill bacteria
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Halide reducing power trend
increases down group (reducing power = > oxidation readiness, i.e loss of e-) bigger molecule lose e- easier
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NaF/NaCl reaction with H2SO4
Na(F/Cl) + H2SO4 --> NaHSO + H(F/Cl)
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NaBr reaction with H2SO4
same as above but reduces farther: 2HBr + H2SO4 -- > Br2 + SO2 + 2H2O
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NaI reaction with H2SO4
same as above but reduces EVEN farther: 6HI + SO2 --> H2S + 3I + 2H2O
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Test for halide
Add dilute HNO3 to remove ions which may interfere with test. Then add few drops AgNO3. ppt formed of silver halide. NB: Test doesnt really work for F since AgF is soluble.
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Eqn of halide test (general)
Ag+ + X- --> AgX
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Colour of AgCl ppt
white
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Colour of AgBr ppt
cream
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Colour of AgI ppt
yellow
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Further test:
add NH3
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Solubility of AgCl
dissolves in dilute NH3
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Solubility of AgBr
dissolves in conc NH3
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Solubility of AgI
doesnt dissolve in conc NH3
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Flame test colours for 1) ca2+ 2) sr2+ 3) ba2+
brick red, red, pale green
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name ammonium ion test
damp red litmus paper. if ammonia present, turns blue.
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test for sulfate ions
add little dilute HCl then BaCl2. if white ppt BaSo4 formed then original compound contained Sulfate
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Test for OH-
hydroxide ions make solutions alkaline. use pH indicatior to test it.
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carbonate ions test
add acid and if it contains carbonates it will fizz. pass gas through limewater and if it turns cloudy then original compound was carbonate
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Other cards in this set

Card 2

Front

State trend in melting points in period 3

Back

Generally increase from Na to Si, and generally decrease from Si to Ar.

Card 3

Front

Explain trend of Na, Mg, Al m.p.

Back

Preview of the front of card 3

Card 4

Front

State and explain Si mp

Back

Preview of the front of card 4

Card 5

Front

Explain behaviour of P4, S8, and Cl2

Back

Preview of the front of card 5
View more cards

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