group 2 - alkaline earth metals

Question 1

which block are group 2 elements found in?

Answer 1

s-block

Question 2

the trend in atomic radius across a period

Answer 2

• atomic radius decreases
• more protons
• similar shielding
• stronger nuclear attraction to outer electron

Question 3

the trend in atomic radius down a group

Answer 3

• atomic radius increases
• more electron shells

Question 4

the trend in ionisation energy down group 2

Answer 4

• ionisation energy decreases
• no. of electron shells increases
• more shielding
• weaker nuclear attr. to electron in outer shell

Question 5

the trend in reactivity down group 2

Answer 5

• reactivity increases
• lower 1st/2nd ionisation energies
• loses electrons & forms +ve ions quicker

Question 6

the trend in melting point down group 2

Answer 6

• melting point decreases
• weaker metallic bonding down group
• as metal ions are bigger
• lower nuclear attr.
• less energy needed to remove outer electron

Question 7

group 2 bonding

Answer 7

• metallic bonds
• giant lattice of cations
• strong electrostatic forces of attr. between the cations and delocalised electrons

Question 8

what type of cations do group 2 metals form?

Answer 8

eg. Mg2+

Question 9

product of metal + cold water –>

(all group 2 elements form this apart from Mg)

Answer 9

metal hydroxide + hydrogen

Question 10

product of metal + steam –>

Answer 10

metal oxide + hydrogen

Question 11

appearance of all oxides

Answer 11

white powders

Question 12

reaction of group 2 elements with water

Answer 12

react more vigorously with water as you go down the group

Question 13

which group 2 element doesn’t react with cold water?

Answer 13

Mg –> only reacts with steam

Question 14

test for Mg

Answer 14

• burns with bright flame
• lit splint goes out with squeak and pop

Question 15

trend in group 2 hydroxide solubilities down the group

Answer 15

increases in solubility

Question 16

Ba(OH)2

Answer 16

• toxic
• fatal consequences if ingested

Question 17

trend in group 2 sulfate solubilities down the group

Answer 17

decreases in solubility

Question 18

BaSO4

Answer 18

• insoluble
• so body won’t absorb it
• barium meals can be used for patients who req. a gastric study

Question 19

ionic formula to form group 2 sulfate

Answer 19

eg. Ca2+(aq) + SO4^2-(aq) –> CaSO4 (s)

Question 20

chemical test to test for presence of sulfates

Answer 20

• add acidified barium chloride
• if sulfate ions are present, a dense, white precipitate of barium sulfate is formed
  (must use HCL or HNO3 instead of H2SO4 to prevent false detection of sulfite ions)

Question 21

chemical test to test for presence of barium

Answer 21

• add H2SO4 to solution which may contain barium
• if barium present, a dense, white precipitate is formed

Question 22

the extraction of titanium

Answer 22

-displacement reaction
-magnesium used
- TiCl4 + 2Mg —> 2MgCl2 + Ti

Question 23

flue gas desulfurisation

Answer 23

-neutralisation reaction
-between calcium oxide and sulfur dioxide