Reaction with water:
Beryllium (Be) + 2H₂O → No reaction.
Magnesium (Mg) + 2H₂O → Mg (OH)₂ + H₂
Calcium (Ca) + 2H₂O → Ca (OH)₂ + H₂
Strontium (Sr) + 2H₂O → Sr (OH)₂ + H₂
Barium (Ba) + 2H₂O → Ba (OH)₂ + H₂
*Magnesium Hydroxide is slightly soluble.
*Calcium Hydroxide forms a white suspension and is slightly soluble.
*Strontium Hydroxide is soluble.
*Barium Hydroxide is soluble.
Down the group:
The reactivity increases.
Atomic radius increases.
The distance between the outer electron decreases.
The outer electrons are more shielded.
Outer electrons are easily donated.
Reaction with dilute sulfuric acid (H₂SO₄):
Beryllium (Be) + H₂SO₄ → BeSO₄ + 2H₂O.
Magnesium (Mg) + H₂SO₄ → MgSO₄ + 2H₂O
Calcium (Ca) + H₂SO₄ → CaSO₄ + 2H₂O
Strontium (Sr) + H₂SO₄ → SrSO₄ + 2H₂O
Barium (Ba) + H₂SO₄ → BaSO₄ + 2H₂O
Reaction with dilute hydrochloric acid (HCl):
Beryllium (Be) + 2HCl → BeCl₂ + H₂.
Magnesium (Mg) + 2HCl → MgCl₂ + H₂
Calcium (Ca) + 2HCl → CaCl₂ + H₂
Strontium (Sr) + 2HCl → SrCl₂ + H₂
Barium (Ba) + 2HCl → BaCl₂ + H₂
Reaction with steam (H₂O):
Beryllium (Be) + 2H₂O (steam) → BeO + 2H₂.
Magnesium (Mg) + H₂O (steam) → MgO + H₂
Calcium (Ca) + H₂O (steam) → CaO + H₂
Strontium (Sr) + H₂O (steam) → SrO + H₂
Barium (Ba) + H₂O (steam) → BaO + H₂
Reaction with oxygen:
Beryllium (Be) + O₂ → BeO (Reacts in a bright white flame)
Magnesium (Mg) + O₂ → MgO (Reacts in a bright white flame)
Calcium (Ca) + O₂ → CaO (Reacts in a brick-red flame)
Strontium (Sr) + O₂ → SrO (Reacts in a red flame)
Barium (Ba) + O₂ → BaO (Reacts in an apple-green flame)
Variation of solubility:
Hydroxides
Down the group 2, the solubility of the hydroxide of each element increases.
Example: Ba (OH)₂ is more soluble than Mg (OH)₂.
Sulfates:
Down the group 2, the solubility of the sulfates of each element decreases.
Example: BeSO₄ is more soluble than SrSO₄.
Oxides:
Down the group 2, the solubility of the oxide of each element increases.
Example: BaO is more soluble than MgO.
Thermal decomposition of nitrates
The thermal decomposition of nitrates involves the release of oxygen gas and the formation of metal oxides.
For example:
2Pb(NO₃)₂(s) → 2PbO(s) + 4NO₂(g) + O₂(g).
2Mg(NO₃)₂(s) → 2MgO(s) + 4NO₂(g) + O₂(g)
The thermal stability of nitrates generally decreases as the size of the metal cation increases down a group in the periodic table.
This is because larger metal cations have weaker bonds with the nitrate ion and are therefore easier to decompose.
Thermal decomposition of carbonates
The thermal decomposition of carbonates also involves the formation of metal oxides, but in this case, carbon dioxide gas is released.
For example:
CaCO₃(s) → CaO(s) + CO₂(g).
Li₂CO₃(s) → Li₂O(s) + CO₂(g)
The thermal stability of carbonates generally decreases as the size of the metal cation increases down a group in the periodic table.
Larger metal cations have weaker bonds with the carbonate ion, making it easier to decompose.
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