Group 2
- Created by: AVAMKX
- Created on: 11-05-18 10:04
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- Trends in group 2 elements
- Ionisation energy decreases down group 2
- Nuclear charge increases so force of attraction for electrons removed increases. (increases ionisation energies)
- Quantum shell added so energy of outer electrons increase making it easier to remove an electron. (decreases ionisation energies)
- Number of inner shells filled increases so shielding increases. (decreases ionisation energies)
- Group 2
- Reactions of group 2 elements
- Water
- Effervescence (bubbles)
- M(s) + 2H2O(l) > M(OH)2 + H2
- Oxygen
- 2M(s) + O2(g) > 2MO(s)
- Bright flame and white solid
- M2+ and O2- ions
- Magnesium and steam
- Forms magnesium oxide (solid) and Hydrogen (gas)
- Water
- Flame tests
- Problems with flame tests
- sodium impurties may mask other colours
- Description of colours are subjective to each individual
- What causes the colours?
- Electrons absorb energy and move from the ground state to an excited state.
- the movement of the electrons back to their ground state releases energy in the form of bright colours
- Problems with flame tests
- Thermal stability of group 2 compounds
- What affects Thermal stability?
- The charge of the cation.
- The ionic radius of the cation
- Thermal stability of nitrates.
- Lesser decomposition occurs for most group 1 nitrates. No brown fumes observed. metal nitrate> metal nitrite + oxygen
- Greater decomposition for all group 2 cations and Lithium. Brown fumes observed. Meal nitrate> metal oxide + Nitrogen dioxide + oxygen
- Thermal stability of carbonates
- No decomposition for most group 1 elements.
- Group 2 elements and lithium decompose. CaCO3 > CaO +CO2
- What affects Thermal stability?
- Reactions of group 2 elements
- Reactivity increases down group 2
- Reactions are more vigorous as you go down the group
- Ionisation energy decreases down group 2
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