3.1.2 group 2

Question 1

Atom radius

Answer 1

Increases down the group

Atoms have more electron shells

Question 2

Melting points

Answer 2

Decreases down the group

Metallic bonding weakens as atomic size increases

Distance between positive ions and delocalised electrons increases

So, electrostatic forces between positive ions and delocalised electrons weakens

Question 3

Second ionisation energy

Answer 3

enthalpy change when one mole of gaseous ions with a single positive charge forms one mole of gaseous ions with a double positive charge

Ti+(g) > Ti+2(g) + e-

Question 4

Reactivity

Answer 4

Increases down the group

As atomic radius increases there is more shielding

Nuclear attraction deceases and it is easier to remove outer electrons

Cations form more easily

Question 5

Reactions with oxygen

Answer 5

Burn in oxygen

Mg burns with bright white flame - MgO is a white solid

Question 6

Reactions with water

Answer 6

Produces oxide and hydrogen

Question 7

Reactions with warm water

Answer 7

Hydroxide + hydrogen

Makes water alkaline

Question 8

Reactions with warm water observations

Answer 8

Fizzing - more vigorous down group

Metal dissolving - faster down group

Solution heating up - more down group

With calcium - white precipitate appearing

Question 9

Reactions with acid

Answer 9

Form salt and hydrogen

Question 10

Metal Oxide + water

Answer 10

Hydroxide formed of varying solubility

Question 11

2 important

Answer 11

Milk of magnesia - used as medicine (Mg(OH)2)

Calcium hydroxide - used in agriculture to neutralise acidic soils

Question 12

Test for CO2

Answer 12

calcium hydroxide (lime water)

Limewater turns cloudy as white calcium carbonate is produced

Ca(OH)2 + CO2 > CaCO3 + H2O