periodicity

Question 1

define periodicity

Answer 1

repeating pattern of physical or chemical properties going across the periods

Question 2

atomic radius across a period

Answer 2

decreases

increased nuclear charge
same shells

Question 3

atomic radius down a group

Answer 3

increases

extra shell
more shielding

Question 4

first ionisation energy across period 3

Answer 4

general increase

increased protons
same shells
smaller radius

Question 5

decrease in IE P to S

Answer 5

S: outer electron paired in 3p; repulsion

Question 6

decrease in IE Mg to Al

Answer 6

Mg has outer in 3s, Al in 3p.

3p easier to remove.

Question 7

Na, Mg, Al mp

Answer 7

metallic bonding
medium
increase Na-Al, greater positive ions and more electrons

Question 8

Si mp

Answer 8

macromolecular

highest

strong covalent tetrahedral structure

Question 9

P, S, Cl mp

Answer 9

low

simple molecular

weak vdw

S is highest, with more electrons and stronger vdw

Question 10

Ar mp

Answer 10

lowest

monoatomic

weak vdw

Question 11

group 2 atomic radius

Answer 11

increases

Question 12

group 2 1IE

Answer 12

decreases

increased shielding
increased radius

Question 13

group 2 melting point

Answer 13

decreases

increased atomic radius in metallic bonding

Question 14

group 2 reactivity

Answer 14

increases

more shielding

easier to lose electron

Question 15

solubility of group 2 hydroxides in water

Answer 15

OH-

increases

Mg least soluble

Question 16

Mg(OH)2 uses

Answer 16

medicine; antacid

sparingly soluble

preferred to calcium carbonate as it will not produce CO2

Question 17

Ca(OH)2 uses

Answer 17

neutralise acidic soils

Question 18

sulfate solubility

Answer 18

decreases

Mg most soluble

Question 19

BaSO4 uses

Answer 19

barium meals

insoluble, toxic if dissolved

opaque to x rats

Question 20

group 2 reactions with water

Answer 20

oxidised

form M2+ ions

metal hydroxide (alkaline) + hydrogen

Question 21

group 2 reaction with steam

Answer 21

white flame

Question 22

flue gas removal

Answer 22

Calcium oxide reacts with sulfur dioxide to remove it from factory pollutants and prevent it from polluting atmosphere

mix calcium oxide or calcium carbonate with water
sprayed onto flue gases
produces solid waste calcium sulfite

Question 23

flue gas equation CaO

Answer 23

CaO(s) + 2H2O(l) + SO2(g) -> CaSO3(s) + 2H2O(l)

Question 24

flue gas equation CaCO3

Answer 24

CaCO3(s) + 2H2O(l) + SO2(g) -> CaSO3(s) + 2H2O(l) +CO2(g)

Question 25

metal extraction

Answer 25

Mg extracts titanium from titanium chloride

can’t use carbon- TiC is formed

cant use electrolysis- not pure enough

Question 26

metal extraction steps

Answer 26

TiO2 solid into TiCl4 liquid at 900 degrees
TiO2 + 2Cl2 + 2C -> TiCl4 + 2CO

TiCl4 purified, distilled in Ag atmosphere

Ti extracted by Mg in Ag atm at 500 degrees
TiCl4 + 2Mg -> Ti + 2MgCl2