1Trends of atomic radius in period3 across 3
Decreases because similar shielding but bigger nuclear charge pulls electrons closer.
2Trends of ionisation energy in period 3 across
Increases because similar shielding but bigger nuclear charge pulling electron closer
3trend across the metals in melting pt?
From Na to Al melting point increases this is because they form cations with a bigger charge so they release more electrons and decrease in atomic radius so stronger electrostatic attractions.
4non metal melting point highest at top
Si
S
P
Cl
Ar
5why is it that order?
Silicon forms a giant covalent lattice with very strong covalent bonds
Sulphur forms largest molecule so forms strongest van der waal forces
Argon doesnt form bonds
6What can you generalise with period 3?
Ionisation energy and atomic radius
7trends of ionisation energy and atomic radius of grp 2?
same as the rest
8general trend of melting point in grp 2? (magnesium doesnt follow this rule it has lowest melting pt)
Decreases since cations become larger so weaker electro static attractions
9what is magnesium used for?
extracting titanium from TiCl4 by reducing it
10use of calcium?
Flue gas desulfurisation to prevent acid rain
11trend of reactiveness of group 2 with water?
increases down the group since ionisation energy decreases
Be doesnt react
Mg barely reacts but reacts strongly with steam to form MgO
Ca to Ra react strongly to form Metal hydroxides. eg: Ca(OH)2
12trend of solubility of grp 2 metal hydroxides with water?
increases down the group
13uses of magnesium hydroxide?
used to cure heart burn since its strong enough to neutralise but not strong enough to damage body cuz of its low solubility
14uses of calcium hydroxide
Used to neutralise acidic soils
15solubility of grp 2 sulfates?
Decreases down group
16use of barium sulfate? BaSO4
used for xray since its almost insoluble and dense enough to absorb xrays
17used of BaCL2?
test for sulfate ions by producing a white precipitate. Acid is first added to remove any carbonates
18Electronegativity trend of group 7?
Decreases down the group
19Boiling point trend of grp 7?
Increases down group since molecules become larger so stronger van der waal forces
20whats oxidising power(reducing power is oppoiste)
ability to gain electrons itself and cause oxidation in another species
21oxidising power trend in grp 7?
Decreases down group. Fluorine can displace any other halogen
22reducing power trend in grp 7?
increases down group
23Reaction of NaCl with H2SO4
Acid base making steamy fumes
Forming NaHSO4 + HCL
24reaction of naBR with H2SO4
Acid base making steamy fumes:
Forming NaHSO4 + HBr
Redox making brown fumes:
Forming Br2 + SO2 + H2O
25reaction of naI with H2SO4
Acid base making steamy fumes:
Forming NaHSO4 + HI
Redox making purple fumes, egg smell, yellow solid (for a bit)
Forming I2 + H2S + H20
But b4 H2S is formed it goes to SO2 then S
26test for halide ions (they form precipitates)
add dilute nitric acid then silver nitrate
F = no precipitate
Cl = white
Br = cream
I = yellow
27trend in solubility of ammonia?
Decreases down group
Dilute ammonia dissolves Cl
Concentrated ammonia dissolves Br
28reaction of Cl2 with water?
Disproportionation reaction forming HCL and HCLO dissociating into H+ Cl- ClO-
ClO kills bacteria
29pros and cons of chlorination?
Pros:
Kills microorganisms
Long lasting
Reduces growth of algae
Cons:
Toxic at high concentrations
Can cause chemical burns
Chloroalkane may form which can cause cancer
30reaction of chlorine with NaOH
Must be in cold dilute aquous NaOH
NaClO + Nacl +H20
31NaClO is active ingrdient of bleach and so what its uses:
Bleaching fabric
Cleaning agent
Treating water