2.21 - Group 2 Flashcards
Write an equation for the first ionisation energy of magnesium…
Mg (g) → Mg⁺(g) + e‾
Explain the shape of this graph:
- first ionisation energy increases across group 3 because of increased nuclear charge, decreased atomic radius and similar electron shielding means more energy is needed to removed the first electron.
- dips at Al because: outer electron is in the 3p orbital, so further from the nucleus and increased shielding from 3s sub level.
- dips at S because the orbital the electron is being removed from contains 2 electrons, meaning there is repulsion between them, so less energy is required to remove one.
What happens to the first ionisation energy as you go down group 2? Why?
- decreases
- number of electrons shells increases down the group
- causing increased shielding and atomic radius
- therefore weaker force between outer electron and nucleus
- therefore less energy is required to remove an electron
How does reactivity with water change as you go down group 2?
- increases (Mg least → Ba most)
- because outer electrons further from nucleus and more electron shielding, so electrons are lost more easily.
Write an equation for the reaction of Barium and water…
- Ba (s) + 2H₂O (l) → Ba(OH)₂ (aq) + H₂ (g)
Write an equation for the reaction of Magnesium and steam…
- Mg (s) + H₂O (g) → MgO (s) + H₂ (g)
What is the trend in hydroxide solubility down group 2?
- increases down the group
Mg(OH)₂ is almost insoluble
Ba(OH)₂ creates a strong alkaline solution
What is the trend in sulphate solubility down group 2?
- decreases down the group
MgSO₄ is soluble
BaSO₄ is insoluble
What is the trend in melting point down group 2? Why?
- decreases down group
- because the delocalised electrons are further from the positive nucleus
- therefore weaker metallic bonds / forces of attraction so less energy is required to overcome these bonds.
What is the trend in atomic radius down group 2?
- increases as there are more occupied electron shells down the group
Write the equations for the extraction of Titanium using Magnesium…
- TiO₂ + 2Cl₂ + C → TiCl₄ + CO₂
- TiCl₄ (l) + 2Mg (s) → 2MgCl₂ (s) + Ti (s)
What are flue gases?
- gases produced by power stations which are harmful to the environment
How can CaO or CaCO₃ be used to remove flue gases? Write equations.
- CaCO₃ (s) + SO₂ (g) → CaSO₃ (s) + CO₂ (g)
- CaO (s) + SO₂ (g) → CaSO₃ (s)
What is Ca(OH)₂ used for? Write an equation related to one of its uses.
- used to neutralise soil
- Ca(OH)₂ (aq) + 2HCl (aq) → 2H₂O (l) + CaCl₂ (aq)
What is Mg(OH)₂ used for?
- milk of magnesia - antacid to treat indigestion, heartburn, wind etc.
