Group 2

Question 1

Atomic radii increases down group 2 because…

Answer 1

1. Atoms have more electron shells.
2. More shielding of nuclear charge.
3. Increased shielding outweighs increased number of protons.
4. Less nuclear attraction for outer electron, so less energy required to remove the outermost electron.

Question 2

Ionisation energies increase down group 2, because:

Answer 2

1. Atoms have more electron shells.
2. More shielding of nucelar charge.
3. Increased shielding outweighs increased number of protons, so electrons are removed/lost more easily.
4. Less nuclear attraction for outer electron, so less energy required to remove outermost electron.

Question 3

Reactivity increases down group 2, because:

Answer 3

1. When group 2 metals react, they form 2+ ions.
2. Removing an electron requires energy; the less energy neeeded to remove the outermost electron, the more reactive the metal.

Question 4

1. Metal + oxygen…
2. Example equs
3. Obs

Answer 4

1. …metal oxide
2. Mg(s) + 1/2O2(g) …. MgO(s) White flame
   Ca(s) + 1/2O2(g) …. Cao(s) Red flame
3. White solid forms

Question 5

1. Metal + water…
2. Example equs
3. Obs

Answer 5

1. …metal hydroxide and hydrogen
2. Ca(s) + 2H2O(l) …. Ca(OH)2(aq) + H2 [pH = 10-11]
   Ba(s) + 2H2O(l) …. Ba(OH)2 + H2(g) [pH = 13-14]
3. Bubbles (efferevesence), solid dissolves

Question 6

1. Metal + steam…
2. Example equs
3. Obs

Answer 6

1. …metal oxide and hydrogen
2. Mg(s) + H2O(g) …. MgO(s) + H2(g)
3. White solid formed.

Question 7

1. Metal oxide + water
2. Example equs
3. Obs

Answer 7

1. …metal hydroxide
2. MgO(s) + H2O(l) …. Mg(OH)2(aq)
3. White solid dissolves.

Question 8

1. Metal + acid…
2. Example equs
3. Obs

Answer 8

1. …metal salt and hydrogen
2. Ca(s) + 2HCl(aq) …. CaCl2(aq) + H2(g)
   Mg(s) + 2HCl(aq) …. MgCl2(aq) + H2(g)
3. Bubbles (effervesence), solid dissolves.

Question 9

1. Metal carbonate + acid…
2. Examples equs
3. Obs

Answer 9

1. …metal salt and carbon dioxide and water
2. SrCO3(s) + 2HCl(aq) …. SrCl2(aq) + CO2(g) + H2O(l)
3. Bubbles (effervesence), solid dissolves.

Question 10

Trend in solubility

Answer 10

The solubility increases down the group and the solutions formed become more alkaline (as increasing number of -OH ions are in solution).
Mg(OH)2- sparingly soluble; pH is 9.
Ca(OH)2- a bit less soluble than Ba(OH)2; pH is 10.
Ba(OH)2- soluble; pH is 13-14.

Question 11

Industrial uses for Ca(OH)2(s)

Answer 11

Use- Neutralise acidic soils.
Explain- Ca(OH)2 is alkaline.

Question 12

Industrial uses for Mg(OH)2

Answer 12

Use- antacid, ingestion remedy.
Explain- Mg(OH)2 neutralises HCl in stomach.

Question 13

Industrial uses for CaCO3

Answer 13

Use- antacid, ingestion remedy.
Explain- CaCO3 neutralises HCl in stomach acid.

Question 14

Testing for CO2 method and equ

Answer 14

1. Bubble gas through limewater.
2. Forms a white precipitate (precipitation) due to CO2 present.
3. Ca(OH)2(aq) + CO2(g) …. CaCO3(s) + H2O(l)