Periodicity (G2+G7)

Question 1

Trend in group 2 reactivity with water?

Answer 1

Reactivity with water increase down group 2

mg reacts rapidly with steam but slowly with cold water

Question 2

Solubility of group 2 sulphates?

Answer 2

Solubility of group 2 sulphates decreases down group 2

BaSO4 insoluble

Question 3

Solubility of group 2 with hydroxides?

Answer 3

Solubility of hydroxides increases down group 2
(Mg(OH)2 very soluble and acts as an antacid)
(Ca(OH)2 reduces soil acidity)

Question 4

Why does group 7 boiling point increase down group?

Answer 4

Molecules have more electrons
Stronger Van see Waals
Requires more energy to overcome

Question 5

What is the trend in oxidising agent ability in group 7 ELEMENTS?

Answer 5

More Oxidising agent down group 7, ability to reduce increases (gain electron when they react)

Question 6

HALIDES trend of reducing agents in group 7?

Answer 6

Halides become more better reducing agents down group 7 (lose electrons)

Valent electron more shielded from nucleus

Question 7

Yellow Solid? 
What has a bad eggy smell? 
Black solid/purole fumes? 
Brown fumes? 
Steamy fumes?

Answer 7

Yellow solid = S 
Eggy smell = H2S 
Black solid / purple fumes = I2 (iodine gas)
Brown fumes = Br2 (bromine gas)
Steamy fumes = HI / HBr

Question 8

Reaction of chlorine with water?

Answer 8

Cl2 + H20 –> HOCl + HCl

Used for water purificiation

Question 9

Reaction of chlorine with sodium hydroxide

Answer 9

Cl2 + 2NaOH –> NaClO + NaCl + H2O

Question 10

What is it called when a species undergoes reduction and oxidation simultaneously?

Answer 10

Disproportionation

Question 11

Names structures

Na, Mg, Al, Si, P, S, Cl, Ar

Answer 11

Na, Mg, Al = Metallic structure ( many strong metallic bonds)

Si = Giant covalent molecular / macromolecular (strong covalent bonds between atoms)

P, S, Cl = simple covalent molecules (covalent bonds between atoms and weak vdw between molecules)

Ar = Monatomic gas (weak vdw forces)

Question 12

In period 3 what elements don’t fit the ionisation energy trend and why?

Answer 12

Al = valent electron shielded by ‘s’ orbital

S = electron shares same orbital so electrons have repulsive forces

Question 13

Group 2 metal and water equations

Answer 13

Metal + 2H2O –> M(OH)2 + H2

Makes hydroxide and hydrogen gas

Question 14

How is titanium oxide/ore (TiO2) converted to Titanium (IV) chloride (TiCl4)?

First reaction conditions and equation to make TiCl4?

Second purification process of TiCl4?

Third reaction condition and equation to make Ti?

Answer 14

1)Chlorine gas and carbon

TiO2 —> TiCl4

2) Fractional distillation of TiCl4
3) 1000 degrees in furnace and Mg

TiCl4 + 2Mg –> Ti + 2MgCl2

Question 15

Use of Calcium oxide and calcium carbonate?

▪▪

Answer 15

▪ Used to remove flue gases via wet scrubbing
(makes calcium sulphate)

▪ Used to neutralise acidic soil

Question 16

Colour of KBr + Cl2?
Colour of KI + Cl2?
Colour of KI + Br2?

Answer 16

1) Orange Solution (from colourless)
2) Brown solution (from colourless)
3) Brown solution (from orange)