Group II - Alkali metals Flashcards
How does the atomic radius change as you go down Group 2?
increases because:
- More electron shells are added.
- Outer electrons are farther from the nucleus.
- Shielding increases, reducing attraction between outer electrons and the nucleus.
What happens to the melting point as you go down Group 2?
decreases except for magnesium (Mg), because:
- Ionic radius increases.
- Delocalised electrons are farther from the nucleus.
- The electrostatic attraction between delocalised electrons and metal ions weakens.
Why is magnesium (Mg) an anomaly in the melting point trend?
Magnesium has an unusually stable crystal structure, which requires less energy to break the bonds, making its melting point lower than expected.
What happens to ionization energy as you go down Group 2?
decreases because:
- Atomic radius increases
- Electron shielding increases
- The nuclear charge increases, but the effect of radius and shielding is stronger, making it easier to lose electrons.
How does reactivity change down Group 2?
increases because:
- Outer electrons are farther from the nucleus
- more shielding
- easier to lose the outer electrons, making the metals more reactive.
How do Group 2 elements react with water?
Group 2 metals react with water to form metal hydroxide and hydrogen gas
Reactivity with water trend:
- Be: No reaction
- Mg: Very slow reaction
- Ca: Steady reaction
- Sr: Fairly quick reaction
- Ba: Rapid reaction
How do Group 2 elements react with oxygen?
When Group 2 metals burn in oxygen, they form metal oxides
Reactivity with oxygen trend:
Reactivity increases down the group, with Ba reacting the fastest and Be reacting the slowest
How do the solubility trends for Group 2 hydroxides and sulfates differ?
- Hydroxides: Become more soluble down the group.
- Sulfates: Become less soluble down the group.
What happens when Group 2 oxides react with water?
- Group 2 oxides (MO) are basic and react with water to form metal hydroxides.
- This reaction increases the pH, making the solution strongly alkaline.
What happens when Group 2 oxides react with water? (general reaction)
MO(s) + H₂O(l) → M(OH)₂(aq)
What is magnesium used for in titanium extraction?
Magnesium is used to extract titanium from its ore, titanium(IV) oxide (TiO₂).
What is the reaction between magnesium and Titanium?
TiCl₄(l) + 2Mg(s) → Ti(s) + 2MgCl₂(s)
Magnesium acts as a reducing agent in this high-temperature reaction
How is calcium hydroxide used in agriculture?
- Calcium hydroxide is used to neutralize acidic soils
- It raises the pH to a level suitable for crop growth.
What is the neutralization reaction for Calcium hydroxide?
H⁺(aq) + OH⁻(aq) → H₂O(l)
How is magnesium hydroxide used as an antacid?
- It neutralizes stomach acid
- helps relieve symptoms of indigestion by reacting with hydrochloric acid
How is barium sulfate used in medical imaging?
- used in X- Ray imaging to highlight soft tissues like the digestive tract
- swallowed as a barium meal, which absorbs X-rays, making organs visible in X-ray images
How do calcium compounds help remove sulfur dioxide from flue gases?
Calcium oxide and Calcium carbonate react with sulfur dioxide in power plants emissions to form calcium sulfite (solid waste product)
Reaction between calcium oxide, calcium carbonate and sulfur dioxide
- CaO(s) + SO₂(g) + H₂O(l) → CaSO₃(s) + H₂O(l)
- CaCO₃(s) + SO₂(g) + H₂O(l) → CaSO₃(s) + H₂O(l) + CO₂(g)
- These reactions help reduce air pollution by removing sulfur dioxide from emissions.
