Topic 4: Group 2 Flashcards
1
Q
Reactions with Oxygen
A
- More vigorous down the group
- Bright flame
- White solid formed
- Barium most reactive
2
Q
Reactions with Chlorine
A
- More vigorous down the group
- Products are chlorides containing M2+ and Cl- ions
3
Q
Reactions with Water
A
- Magnesium reacts v slowly
- More vigorous down the group
Products:
1. Hydrogen gas
2. hydroxides
4
Q
Oxides with water
A
Form colourless solutions
Form hydroxide ions
5
Q
Trend in solubility of hydroxides
A
Solubility increases down the group.
6
Q
Trend in solubility of sulphates
A
Solubility decreases down the group.
7
Q
Test for sulphate ions
A
Add barium chloride/nitrate
Sulphate ions react to form a white precipitate of Barium sulphate.
8
Q
Thermal decomposition of nitrates produce…
A
9
Q
Trend in thermal stability of carbonates and nitrates
A
- More thermally stable as you go down group because:
1. Ionic radius increases down group
2. charge density decreases
3. large ions have less polarising ability on carbonate/nitrate ion
4. more energy is needed to break the C-O / N-O bond.
10
Q
Equation for G2 carbonates and heat
A
MCO3 –> MO + CO2
11
Q
Equation for G2 nitrates and heat
A
M(NO3)2 –> 2MO + 4NO2 + O2
12
Q
What is NO2
A
Brown gas
13
Q
How to do a flame test?
A
- Dip nichrome wire in c. HCl
- Then into the compound to be tested
- Hold in blue part of flame
14
Q
What is the c.HCl used for?
A
15
Q
What causes the flame test?
A
- Electrons in the metal ions are excited to higher electronic energy levels.
- As the electrons return to the ground state, the energy is emitted as visible light.
- The light emitted is characteristic of that metal as each metal has energy levels with different energy gaps between them.
