group 2

Question 1

block group 2 elements are in

Answer 1

s - block

Question 2

why are group 2 elements in the s - block

Answer 2

highest energy electron occupies an s orbital

Question 3

physical properties

Answer 3

giant metallic structure
good electrical conductors as they have mobile delocalised electrons which can move and carry a charge
high melting and boiling point as lots of energy is required to break the strong metallic bonds

Question 4

as a group 2 element loses 2 electrons…

Answer 4

it undergoes oxidation causing reduction

Question 5

group 2 trends - atomic radii

Answer 5

the atomic radii increases as you go down group 2
there are more shells
more shielding effect by inner shell electrons
increased distance of the outer electron from the nucleus and increased shielding effect far outweigh increase in nuclear charge
nuclear attraction on the outer shell electron decreases down group 2 and this means the atomic radius will increase

Question 6

group 2 trends - ionisation energy

Answer 6

first ionisation energy decreases as you go down group 2
atomic radius increases
more shells
more shielding effect by inner shell electrons
increased distance of the outer electron from the nucleus and the increased shielding effect far outweigh increase in nuclear charge
nuclear attraction on the outer shell electron decreases
less energy is needed to remove an electron from the outer shell of the group 2 atom and so first ionisation energy decreases

Question 7

first ionisation energy of Sr

Answer 7

Sr(g) —> Sr+(g) + e-

Question 8

second ionisation energy of Sr

Answer 8

Sr+ (g) —> Sr 2+ (g) + e-

Question 9

trend in reactivity down group 2

Answer 9

atomic radius increases
more shells
more shielding effect by inner shell electrons
increased distance of outer electron from the nucleus and increased shielding effect far outweigh increase in nuclear charge
weaker nuclear attraction on the outer shell electrons
ionisation energy decreases
less energy is needed to remove the 2 electrons from the outer shell of the group 2 atom
reactivity decreases down group 2

Question 10

reaction of group 2 element with oxygen

Answer 10

metal + oxygen —> metal oxide

Question 11

reaction of group 2 element with water

Answer 11

metal + water —> metal hydroxide + hydrogen

Question 12

magnesium + steam

Answer 12

magnesium oxide + hydrogen

Question 13

base

Answer 13

proton acceptors

Question 14

oxidising agent

Answer 14

reduced

Question 15

reducing agent

Answer 15

oxidised

Question 16

metal oxide + water –> metal hydroxide

Question 17

solubility in group 2

Answer 17

solubility increases down the group

Question 18

alkalinity in group 2

Answer 18

alkalinity increases down group 2

Question 19

why does Ba(OH)2 have a greater PH than Ca(OH)2

Answer 19

Ba(OH)2 is more soluble than Ca(OH)2, more ions are released in solution and as concentration of OH- increases, alkalinity increases

Question 20

Mg(OH)2 use and reason

Answer 20

used in indigestion tablets as an antacid by neutralises HCl

Question 21

Ca(OH)2 use and reason

Answer 21

used in agriculture to neutralise acid soil by reacting with acid substances in the soil

Question 22

thermal decomposition

Answer 22

breaking up of a chemical substance with/by heat into at least two chemical substances

Question 23

thermal decomposition of calcium carbonate

Answer 23

CaCO3 (s) –> CaO (s) + CO2 (g)

Question 24

decomposition trend in the group

Answer 24

carbonates become more difficult to decompose with heat as yo move down the group so thermal stability increases down the group

Question 25

why are group 2 elements known as reducing agents

Answer 25

group 2 elements loose 2 electrons so are oxidised themselves and are also electron donors