Group 2 Flashcards
1
Q
Atomic radii increases down group 2 because…
A
- Atoms have more electron shells.
- More shielding of nuclear charge.
- Increased shielding outweighs increased number of protons.
- Less nuclear attraction for outer electron, so less energy required to remove the outermost electron.
2
Q
Ionisation energies increase down group 2, because:
A
- Atoms have more electron shells.
- More shielding of nucelar charge.
- Increased shielding outweighs increased number of protons, so electrons are removed/lost more easily.
- Less nuclear attraction for outer electron, so less energy required to remove outermost electron.
3
Q
Reactivity increases down group 2, because:
A
- When group 2 metals react, they form 2+ ions.
- Removing an electron requires energy; the less energy neeeded to remove the outermost electron, the more reactive the metal.
4
Q
- Metal + oxygen…
- Example equs
- Obs
A
- …metal oxide
- Mg(s) + 1/2O2(g) …. MgO(s) White flame
Ca(s) + 1/2O2(g) …. Cao(s) Red flame - White solid forms
5
Q
- Metal + water…
- Example equs
- Obs
A
- …metal hydroxide and hydrogen
- Ca(s) + 2H2O(l) …. Ca(OH)2(aq) + H2 [pH = 10-11]
Ba(s) + 2H2O(l) …. Ba(OH)2 + H2(g) [pH = 13-14] - Bubbles (efferevesence), solid dissolves
6
Q
- Metal + steam…
- Example equs
- Obs
A
- …metal oxide and hydrogen
- Mg(s) + H2O(g) …. MgO(s) + H2(g)
- White solid formed.
7
Q
- Metal oxide + water
- Example equs
- Obs
A
- …metal hydroxide
- MgO(s) + H2O(l) …. Mg(OH)2(aq)
- White solid dissolves.
8
Q
- Metal + acid…
- Example equs
- Obs
A
- …metal salt and hydrogen
- Ca(s) + 2HCl(aq) …. CaCl2(aq) + H2(g)
Mg(s) + 2HCl(aq) …. MgCl2(aq) + H2(g) - Bubbles (effervesence), solid dissolves.
9
Q
- Metal carbonate + acid…
- Examples equs
- Obs
A
- …metal salt and carbon dioxide and water
- SrCO3(s) + 2HCl(aq) …. SrCl2(aq) + CO2(g) + H2O(l)
- Bubbles (effervesence), solid dissolves.
10
Q
Trend in solubility
A
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.
11
Q
Industrial uses for Ca(OH)2(s)
A
Use- Neutralise acidic soils.
Explain- Ca(OH)2 is alkaline.
12
Q
Industrial uses for Mg(OH)2
A
Use- antacid, ingestion remedy.
Explain- Mg(OH)2 neutralises HCl in stomach.
13
Q
Industrial uses for CaCO3
A
Use- antacid, ingestion remedy.
Explain- CaCO3 neutralises HCl in stomach acid.
14
Q
Testing for CO2 method and equ
A
- Bubble gas through limewater.
- Forms a white precipitate (precipitation) due to CO2 present.
- Ca(OH)2(aq) + CO2(g) …. CaCO3(s) + H2O(l)
