Group 2 Flashcards

Active recall practice for physical property trends, reactions, solubilities, and thermal decomposition.

Trends in Physical Properties: read all 5 questions and answers

State the trend in atomic radius down Group 2 and explain why.
Increases: the number of filled electron shells increases, which increases shielding and overrides the effect of the increasing nuclear charge.
Explain why the first ionisation energy of Group 2 elements decreases down the group.
Outer electrons are in shells further from the nucleus and experience more shielding, reducing the electrostatic attraction between the nucleus and outer electrons.
Describe the general trend in melting points down Group 2 and explain why.
Generally decreases: atomic radius increases, so the distance between the metal cations and the delocalised electrons increases, weakening the metallic bonding.
Why is Magnesium's melting point anomalously low compared to the Group 2 trend?
Magnesium has a different crystal structure (hexagonal close packed, HCP) compared to calcium and strontium (face-centered cubic, FCC), which alters the lattice arrangement and metallic bond strength, without any difference in packing efficiency (both are close-packed at ~74%).
What is the general electronic configuration of the outer shell of Group 2 elements?
\(ns^2\).

Reactions of Group 2 Metals: read all 6 questions and answers

Write the equation for the reaction of Calcium with cold water, including state symbols.
Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g).
Describe the observations and products when Magnesium reacts with steam.
Bright white light and white solid form; products are magnesium oxide (MgO) and hydrogen gas (H₂).
Write the equation for the reaction of Magnesium with steam, including state symbols.
Mg(s) + H₂O(g) → MgO(s) + H₂(g).
Why does the reactivity of Group 2 elements with water increase down the group?
First and second ionisation energies decrease, making it easier for the atoms to lose their two outer electrons and form 2+ ions.
Write the equation for the reaction of Strontium with hydrochloric acid, including state symbols.
Sr(s) + 2HCl(aq) → SrCl₂(aq) + H₂(g).
What is the role of the Group 2 metal when it reacts with water or acids?
Reducing agent (it is oxidised as it loses electrons).

Solubility & Uses of Compounds: read all 5 questions and answers

State the trend in solubility of Group 2 hydroxides down the group.
Solubility increases (Mg(OH)₂ is sparingly soluble, Ba(OH)₂ is highly soluble).
State the trend in solubility of Group 2 sulfates down the group.
Solubility decreases (MgSO₄ is soluble, BaSO₄ is insoluble).
Why is Barium Sulfate used in medicine as a Barium meal despite barium ions being toxic?
It is highly insoluble, so it is not absorbed into the bloodstream. It absorbs X-rays to outline the gut.
State a medical use of Magnesium Hydroxide and explain how it works.
Used as an antacid (milk of magnesia) to neutralise excess stomach acid (hydrochloric acid).
What is Calcium Hydroxide (slaked lime) used for in agriculture?
To neutralise acidic soils and raise soil pH.

Flame Tests & Thermal Decomposition: read all 4 questions and answers

State the flame test colours for Calcium, Strontium, and Barium cations.
Ca²⁺: brick red; Sr²⁺: red (crimson); Ba²⁺: apple green.
State the trend in the thermal stability of Group 2 carbonates down the group.
Thermal stability increases (they require higher temperatures to decompose).
Explain, in terms of polarising power, why the thermal stability of Group 2 carbonates increases down the group.
Down the group, cation size increases and charge density decreases. Cations have less polarising power, so they distort the carbonate anion less, making it harder to break covalent bonds within it.
Write the equation for the thermal decomposition of Calcium Carbonate, including state symbols.
CaCO₃(s) → CaO(s) + CO₂(g).