Periodic Table And Such

Question 1

Atomic radius down group 2

Answer 1

Increase
(More shells)

Question 2

Ionisation energy down group 2

Answer 2

Decrease
(More shells = more distance = less effective nuclear charge = less energy required)

Question 3

Electronegativity down group 2

Answer 3

Decreases
(More shells = more shielding and more distance = less effective nuclear charge = less electronegative)

Question 4

GROUP 2
Reactions with water

Answer 4

BERYLLIUM
Reacts with steam at high temps (but basically doesn’t react)
MAGNESIUM
Burns in steam; slight reaction with cold water but forms magnesium hydroxide layer which is insoluble and acts as barrier and also hydrogen
CALCIUM STRONTIUM BARIUM
All react with water with increasing vigour to make (group 2) hydroxide and hydrogen

Question 5

GROUP 2
Reactions with Oxygen

Answer 5

BERYLLIUM
Burns (when powdered)
ALL OTHERS
Burn to make metal oxide

Question 6

GROUP 2
Reactions with (dilute) HCl (hydrochloric acid)

Answer 6

All react to form metal chloride and H2 gas
Reactions get more vigorous down the group

Question 7

GROUP 2
Reactions with (dilute) sulphuric acid

Answer 7

BERYLLIUM AND MAGNESIUM
Similar to HCl; react to form metal sulphate and H2 gas
CALCIUM STRONTIUM BARIUM
Form insoluble/ partially insoluble metal sulphates so layer of insoluble sulphate forms

Question 8

GROUP 2
Reaction with nitric acid

Answer 8

BERYLLIUM
Can’t tell. Beryllium is Quirky and scientists can’t agree about it
ALL OTHERS
Produce hydrogen gas and metal nitrate

Question 9

GROUP 2 HYDROXIDES SOLUBILITY

Answer 9

Increase as you go down the group
Larger ionic radius for same ionic charge so charge density decreases so less energy required for lattice dissociation (breaking bonds)
Same hydration enthalpy (forming bonds)
Breaking bonds releases more energy than forming them so more likely to dissolve.
MAGNESIUM: insoluble
CALCIUM: slightly soluble
STRONTIUM AND BARIUM: Soluble

Question 10

GROUP 2 SULPHATES SOLUBILITY

Answer 10

Decrease down group
Lattice dissociation enthalpy is relatively constant down the group but hydration enthalpy decreases
So less likely to dissolve and form new bonds with water molecules
MAGNESIUM AND CALCIUM: Soluble
STRONTIUM: insoluble
BARIUM: insoluble

Question 11

GROUP 2 CARBONATES SOLUBILITY

Answer 11

Decreases down group
Basically insoluble

Question 12

GROUP 2 CARBONATES THERMAL STABILITY

Answer 12

More stable down the group
More shells = less charge dense = less polarising = more stable
Decompose to form group 2 oxide and CO2

Question 13

GROUP 2 NITRATES THERMAL STABILITY

Answer 13

Thermal stability increases down group
More shells = less charge dense = less polarising = more stable
Decompose to form group 2 oxide and nitrogen dioxide and oxygen

Question 14

Atomic radius down group 7

Answer 14

Increase
(More shells)

Question 15

Electronegativity down group 7

Answer 15

Decrease
(Charge density and electron shielding decrease with more shells)

Question 16

Melting and boiling temperatures down group 7

Answer 16

More electrons as you go down
London forces increase
So harder to separate
So melting point and boiling point increase

Question 17

Oxidising power down group 7

Answer 17

OIL
F doesn’t lose any
So oxidising power decreases down group

Question 18

GROUP 7 REACTION WITH HYDROGEN

Answer 18

All make hydrogen halide (HX)
FLUORINE
Explosive explosive
CHLORINE
Explosive exposed to sunlight or flame- makes
BROMINE
Mild explosion in flame
IODINE
Only combine partially even under constant heat (reversible reaction, too)

Question 19

GROUP 7 REACTION WITH PHOSPHORUS

Answer 19

ALL halogens react with phosphorous to form trihalides (phosphorus (|||) halides)
EXCESS CHLORINE OR BROMINE forms pentahalides (phosphorus (V) halides)

Question 20

GROUP 7 REACTIONS WITH SODIUM

Answer 20

ALL react to produce sodium halides

Question 21

GROUP 7 REACTIONS WITH IRON

Answer 21

IRON burns in ALL HALOGEN GASES (except iodine) to give iron (|||) halides
IODINE: only produces iron (||) iodide

Question 22

GROUP 7 REACTIONS with iron (||) ions

Answer 22

FLUORINE: it’s solution. Won’t work with fluorine, it just reacts with the water
CHLORINE AND BROMINE: oxidise iron (||) to iron (|||) ions. Cl and Br are reduced in the process.
IODINE (in iron (|||)): weak. It is oxidised. (Iron (|||) => Iron (||), and I- => I)

Question 23

GROUP 7 REACTIONS with SODIUM HYDROXIDE SOLUTION

Answer 23

CHLORINE: DISPROPORTIONATION REACTION
In cold dilute NaOH => bleach (NaCl + NaClO + H2O)
In hot NaOH => sodium chlorate (V) (NaCl + NaClO3 + H2O)

Question 24

HYDROGEN HALIDES BOILING POINTS

Answer 24

HF high (London and hydrogen bond)
Decrease to HCl (no hydrogen bond)
From HCl to HI (increasing London)

Question 25

MAKING HYDROGEN HALIDES

Answer 25

Sodium (halide) + sulphuric acid => hydrogen halide + NaHSO4 NaCl + H2SO4 => HCl + NaHSO4 BUT not for iodine; too strong at reducing, so just reduces the sulphur

Question 26

ACIDITY OF HYDROGEN HALIDES

Answer 26

ALL STRONG ACIDS EXCEPT HF HF: ionises, but forms an ion pair, so water ions are bound to F- ion So less effective as an acid

Question 27

HALIDE IONS AS REDUCING AGENTS

Answer 27

RIL Less electronegative down the group Better at losing electrons So better reducers

Question 28

TESTING FOR HALIDE IONS

Answer 28

1. Nitric acid (to prevent formation of other silver salts) 2. Silver nitrate: F- = no ppt Cl- = white ppt Br- = cream ppt I- = yellow ppt 3. Ammonia solution (dilute) AgCl = ppt dissolves AgBr and AgI = ppt remains 4. Ammonia solution (concentrate) AgBr = ppt dissolves AgI = ppt remains

Question 29

TESTING FOR SULPHATE IONS

Answer 29

Use BaCl BaCl reacts with sulphate to make: - Barium sulphate (white ppt) - Halogen chloride

Question 30

TESTING FOR CARBONATE/ HYDROGEN CARBONATES

Answer 30

1. React with HCl - Forms CO2 and metal salt (HCl) and water 2. Test for CO2 using limewater - Turns cloudy

Question 31

TESTING FOR AMMONIUM COMPOUNDS

Answer 31

1. Add NaOH - Ammonia gas is alkaline, so check for it using damp (red) litmus paper - Turns blue if ammonia gas present

Question 32

MANUFACTURING CHLORINE

Answer 32

1. Put in sodium chloride solution (sodium, chloride, OH- and H+ ions present) 2. Cl- and OH- ions gather at anode - Cl is less electronegative than H so it loses electrons more easily so is discharged from solution - Two chloride ions each are oxidised and combine to form Cl2 gas 3. H+ and Na+ ions gather at cathode - H is more electronegative than Na so it gains electrons more easily so is discharged from solution - Two H+ ions are each reduced to form H2 gas - Position of equilibrium shifts and H2O turns into more OH- and H+ ions, leading to congregation of OH- and Na+ ions around cathode: combine to form NaOH Note: diaphragm used to separate anode and cathode; - If Cl reacts with H2, explosive mixture created and HCl gas - If Cl reacts with NaOH, mixture of sodium chloride and sodium chlorate (|) (bleach)

Question 33

GROUP 1 vs GROUP 2 COMPOUNDS: Thermal stability

Answer 33

Group 1 = lower ionic charge so less polarising so more stable

Question 34

GROUP 1 CARBONATES: Thermal stability

Answer 34

Thermally stable. Don’t decompose

Question 35

GROUP 1 NITRATES: Thermal stability

Answer 35

Decompose to form respective nitrite and oxygen

Question 36

GROUP 1 FLAME TESTS

Answer 36

Lithium: bright red Sodium: bright yellow Potassium: lilac Rubidium: red/ violet Caesium: blue/ violet

Question 37

GROUP 2 FLAME TESTS

Answer 37

Beryllium: no colour Magnesium: no colour Calcium: brick red Strontium: bright red Barium: pale green