group 2

Question 1

pattern of group 2 ionisation energy

Answer 1

ionisation energy decreases down the group
* nuclear charge increases
* outweighted by increasing shielding effect
* atomic radius increases

Question 2

reaction of group 2 with oxygen when burning in air

Mg, Ca, Sr, Ba with O₂

Answer 2

silver-gray solids (group 2 metals) reacts with oxygen to form white solid (group 2 oxides)

flame color:
Mg 🠒 brilliant white
Ca 🠒 brick red
Sr 🠒 crimson red
Ba 🠒 green

Question 3

reaction of group 2 oxides with water

MgO, CaO, SrO, BaO with H₂O

Answer 3

• forms hydroxides
• the solution formed becomes more alkaline down the group

Question 4

solubility of group 2 hydroxides

Mg(OH)₂, Ca(OH)₂, Sr(OH)₂, Ba(OH)₂

Answer 4

solubility increases down the group

thus pH level increases (more basic)

Question 5

solubility of group 2 sulfates

MgSO₄, CaSO₄, SrSO₄, BaSO₄

Answer 5

decreases down the group

Question 6

reaction of group 2 hydroxides with acid

Mg(OH)₂, Ca(OH)₂, Sr(OH)₂, Ba(OH)₂ with H₂SO₄/HCl

Answer 6

forms salt (group 2 sulfate or chlorides - e.g. MgSO₄ or MgCl₂) and H₂O

neutralisation reaction

Question 7

solubility of group 2 carbonates

MgCO₃, CaCO₃, SrCO₃, BaCO₃

Answer 7

all insoluble in water

therefore does not react with water but only with acid

Question 8

thermal decomposition of group 2 carbonates

MgCO₃, CaCO₃, SrCO₃, BaCO₃

Answer 8

white solid (carbonates) decomposed to form another white solid (oxides) and CO₂ gas

e.g. MgCO₃ (s) 🠒 MgO (s) + CO₂ (g)

Question 9

thermal decomposition pattern of group 2 carbonates

Mg(NO₃)₂, Ca(NO₃)₂, Sr(NO₃)₂, Ba(NO₃)₂

Answer 9

temperature needed to decompose carbonates increases descending down the group

thus the increase in thermal stability

Question 10

thermal decomposition of group 2 nitrates

Mg(NO₃)₂, Ca(NO₃)₂, Sr(NO₃)₂, Ba(NO₃)₂

Answer 10

white solid (carbonates) decomposed to form another white solid (oxides), toxic brown NO₂ gas and O₂

e.g. Mg(NO₃)₂ (s) 🠒 MgO (s) + 2NO₂ (g) + 1/2O₂ (g)

Question 11

thermal decomposition pattern of group 2 nitrates

Mg(NO₃)₂, Ca(NO₃)₂, Sr(NO₃)₂, Ba(NO₃)₂

Answer 11

temperature needed to decompose nitrates increases descending down the group

thus the increase in thermal stability