Group 2

State the electron configuration of the outer shell for Group 2 elements.

ns² (where n is the principal quantum number of the outer shell).

State the block of the periodic table that Group 2 elements belong to.

s-block (the highest energy electron occupies an s orbital).

State the electron configuration of beryllium.

1s² 2s².

State the electron configuration of magnesium.

1s² 2s² 2p⁶ 3s².

State the electron configuration of calcium.

1s² 2s² 2p⁶ 3s² 3p⁶ 4s².

State the electron configuration of strontium.

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s².

State the electron configuration of barium.

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s².

State the electron configuration of radium.

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s².

State the structure and bonding of Group 2 elements.

Giant metallic lattice; strong electrostatic attraction between positive metal ions (cations) and delocalised electrons.

Explain why Group 2 elements are good electrical conductors.

They have mobile delocalised electrons which are free to move and carry charge.

Explain why Group 2 elements have high melting and boiling points.

A lot of energy is required to break the strong metallic bonds between positive ions and delocalised electrons.

State the oxidation state of Group 2 elements when they react.

+2 (they lose 2 electrons to form M²⁺ ions).

State the trend in atomic radius down Group 2.

Atomic radius increases down the group.

Explain the trend in atomic radius down Group 2.

There are more shells of electrons; more shielding effect by inner shell electrons; increased distance of the outer electron from the nucleus outweighs the increased nuclear charge; nuclear attraction on outer-shell electrons decreases; atomic radius increases.

State the trend in first ionisation energy down Group 2.

First ionisation energy decreases down the group.

Explain the trend in first ionisation energy down Group 2.

Atomic radius increases; more shells; more shielding; increased distance and shielding outweigh increased nuclear charge; nuclear attraction on outer-shell electrons decreases; less energy is needed to remove an electron from the outer shell.

State the trend in reactivity down Group 2.

Reactivity increases down the group.

Explain the trend in reactivity down Group 2.

Atomic radius increases; more shells; more shielding; increased distance and shielding outweigh increased nuclear charge; weaker nuclear attraction on outer-shell electrons; first and second ionisation energies decrease; less energy is needed to remove the 2 outer electrons; reactivity increases.

State the equation for the first ionisation energy of strontium including state symbols.

Sr(g) → Sr⁺(g) + e⁻.

State the equation for the second ionisation energy of strontium including state symbols.

Sr⁺(g) → Sr²⁺(g) + e⁻.

State the general equation for the reaction of a Group 2 metal with oxygen.

2M(s) + O₂(g) → 2MO(s).

State the equation for the reaction of magnesium with oxygen including state symbols.

2Mg(s) + O₂(g) → 2MgO(s).

State the oxidation and reduction in the reaction of magnesium with oxygen.

Mg is oxidised: oxidation number increases from 0 to +2; O is reduced: oxidation number decreases from 0 to -2.

State the observation when magnesium burns in oxygen.

Bright white flame.

State the equation for the reaction of calcium with oxygen including state symbols.

2Ca(s) + O₂(g) → 2CaO(s).

State the oxidation and reduction in the reaction of calcium with oxygen.

Ca is oxidised: oxidation number increases from 0 to +2; O is reduced: oxidation number decreases from 0 to -2.

State the general equation for the reaction of a Group 2 metal with water.

M(s) + 2H₂O(l) → M(OH)₂(aq) + H₂(g).

State the equation for the reaction of calcium with water including state symbols.

Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g).

State the oxidation and reduction in the reaction of calcium with water.

Ca is oxidised: oxidation number increases from 0 to +2; H is reduced: oxidation number decreases from +1 to 0.

State the observations when calcium reacts with water.

Effervescence/fizzing/bubbles of gas; solid dissolves/disappears; colourless solution forms.

State the equation for the reaction of strontium with water including state symbols.

Sr(s) + 2H₂O(l) → Sr(OH)₂(aq) + H₂(g).

State the equation for the reaction of barium with water including state symbols.

Ba(s) + 2H₂O(l) → Ba(OH)₂(aq) + H₂(g).

State the reaction of magnesium with cold water.

Magnesium reacts very slowly with cold water.

State the equation for the reaction of magnesium with steam including state symbols.

Mg(s) + H₂O(g) → MgO(s) + H₂(g).

State the observation when magnesium reacts with steam.

Bright white flame; very vigorous reaction.

State the general equation for the reaction of a Group 2 metal with a dilute acid.

M(s) + 2HCl(aq) → MCl₂(aq) + H₂(g) (or with other acids: M + 2H⁺ → M²⁺ + H₂).

State the equation for the reaction of magnesium with hydrochloric acid including state symbols.

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g).

State the oxidation and reduction in the reaction of magnesium with hydrochloric acid.

Mg is oxidised: oxidation number increases from 0 to +2; H is reduced: oxidation number decreases from +1 to 0.

State the equation for the reaction of calcium with hydrochloric acid including state symbols.

Ca(s) + 2HCl(aq) → CaCl₂(aq) + H₂(g).

State the observations when a Group 2 metal reacts with a dilute acid.

Effervescence/fizzing/bubbles of gas; solid dissolves/disappears.

State the general equation for the reaction of a Group 2 oxide with water.

MO(s) + H₂O(l) → M(OH)₂(aq).

State the equation for the reaction of calcium oxide with water including state symbols.

CaO(s) + H₂O(l) → Ca(OH)₂(aq).

State the equation for the reaction of magnesium oxide with water including state symbols.

MgO(s) + H₂O(l) → Mg(OH)₂(aq).

State the pH of the solution formed when a Group 2 oxide reacts with water.

pH between 10 and 12 (alkaline).

Explain why the solutions formed when Group 2 oxides react with water are alkaline.

The oxide reacts with water to form the metal hydroxide; this releases OH⁻ ions in solution.

State the trend in alkalinity of Group 2 hydroxide solutions down the group.

Alkalinity increases down the group.

Explain the trend in alkalinity of Group 2 hydroxide solutions down the group.

Solubility of Group 2 hydroxides increases down the group; more OH⁻ ions are released in solution; as concentration of OH⁻ increases, alkalinity increases.

State the equation for the dissolution of calcium hydroxide in water.

Ca(OH)₂(s) + (aq) → Ca²⁺(aq) + 2OH⁻(aq).

Explain why Ba(OH)₂(aq) has a greater pH than Ca(OH)₂(aq).

Ba(OH)₂ is more soluble than Ca(OH)₂; more OH⁻ ions are released in solution; as concentration of OH⁻ increases, alkalinity increases.

State the general equation for the reaction of a Group 2 oxide with an acid.

MO(s) + 2HCl(aq) → MCl₂(aq) + H₂O(l).

State the equation for the reaction of magnesium oxide with hydrochloric acid including state symbols.

MgO(s) + 2HCl(aq) → MgCl₂(aq) + H₂O(l).

State the observations when a Group 2 oxide reacts with an acid.

Solid dissolves.

State the general equation for the reaction of a Group 2 hydroxide with an acid.

M(OH)₂(s) + 2HCl(aq) → MCl₂(aq) + 2H₂O(l).

State the equation for the reaction of calcium hydroxide with hydrochloric acid including state symbols.

Ca(OH)₂(s) + 2HCl(aq) → CaCl₂(aq) + 2H₂O(l).

State the general equation for the reaction of a Group 2 carbonate with an acid.

MCO₃(s) + 2HCl(aq) → MCl₂(aq) + CO₂(g) + H₂O(l).

State the equation for the reaction of calcium carbonate with hydrochloric acid including state symbols.

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l).

State the observations when a Group 2 carbonate reacts with an acid.

Solid dissolves; effervescence/fizzing/bubbles of gas (CO₂).

State the general equation for the thermal decomposition of a Group 2 carbonate.

MCO₃(s) → MO(s) + CO₂(g).

State the equation for the thermal decomposition of calcium carbonate including state symbols.

CaCO₃(s) → CaO(s) + CO₂(g).

State the equation for the thermal decomposition of strontium carbonate including state symbols.

SrCO₃(s) → SrO(s) + CO₂(g).

State the trend in thermal stability of Group 2 carbonates down the group.

Thermal stability increases down the group; carbonates become more difficult to decompose with heat down the group.

State the use of calcium hydroxide in agriculture.

Calcium hydroxide (Ca(OH)₂) is used in agriculture to neutralise acid soils; raises soil pH from acidic towards neutral.

State the equation for the neutralisation of acid soils using calcium hydroxide.

Ca(OH)₂(s) + 2H⁺(aq) → Ca²⁺(aq) + 2H₂O(l).

State the use of magnesium hydroxide and calcium carbonate in medicine.

Mg(OH)₂ and CaCO₃ are used as antacids to treat indigestion; they neutralise excess stomach acid.

State the equation for magnesium hydroxide neutralising stomach acid.

Mg(OH)₂(s) + 2HCl(aq) → MgCl₂(aq) + 2H₂O(l).

State the equation for calcium carbonate neutralising stomach acid.

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l).

State the equation for the reaction of calcium with nitrogen to form calcium nitride.

3Ca(s) + N₂(g) → Ca₃N₂(s).

State the equation for the reaction of calcium phosphide formation.

6Ca(s) + P₄(s) → 2Ca₃P₂(s).

State the equation for the reaction of calcium nitride with water.

Ca₃N₂(s) + 6H₂O(l) → 3Ca(OH)₂(aq) + 2NH₃(g).

Identify the products formed when calcium nitride reacts with water.

Calcium hydroxide (Ca(OH)₂) and ammonia (NH₃); both are alkaline.

State the equation for the reaction of barium nitride with water.

Ba₃N₂(s) + 6H₂O(l) → 3Ba(OH)₂(aq) + 2NH₃(g).

Identify the products formed when barium nitride reacts with water.

Barium hydroxide (Ba(OH)₂) and ammonia (NH₃); both are alkaline.

Describe the structure and bonding of Group 2 compounds such as Ca₃N₂.

Giant ionic lattice.

Explain why Group 2 compounds such as Ca₃N₂ have giant ionic structures.

They are formed between metal cations (Ca²⁺) and non-metal anions (N³⁻); strong electrostatic attraction between oppositely charged ions.

Explain why barium reacts more vigorously with bromine than calcium.

Ba has a greater atomic radius than Ca; Ba has more shells/more shielding; nuclear attraction is less in Ba; less energy is needed to lose the outer electrons; reactivity increases down Group 2.

Explain why the reaction of barium with water is more vigorous than calcium with water.

Ba has a greater atomic radius than Ca; Ba has more shells/more shielding; nuclear attraction is less in Ba; less energy is needed to lose the outer electrons; reactivity increases down Group 2.

State the equation for the formation of barium peroxide.

Ba(s) + O₂(g) → BaO₂(s) (at 500°C with excess oxygen).

State the structure of the peroxide ion.

[O-O]²⁻.

State the use of calcium oxide.

Calcium oxide (CaO) is used to convert acidic soil pH to neutral.

State the use of calcium carbonate.

Calcium carbonate (CaCO₃) is used as an antacid and in agriculture to neutralise acid soils.

Define the term 'thermal decomposition'.

The breaking up of a chemical substance with heat into at least two chemical substances.

State the equation for the reaction of barium with oxygen.

2Ba(s) + O₂(g) → 2BaO(s).

State the equation for the reaction of strontium with oxygen.

2Sr(s) + O₂(g) → 2SrO(s).

State the oxidation and reduction in the reaction of strontium with oxygen.

Sr is oxidised: oxidation number increases from 0 to +2; O is reduced: oxidation number decreases from 0 to -2.

State the equation for the reaction of strontium oxide with water.

SrO(s) + H₂O(l) → Sr(OH)₂(aq).

State the equation for the reaction of barium oxide with water.

BaO(s) + H₂O(l) → Ba(OH)₂(aq).

State the equation for the reaction of strontium carbonate with hydrochloric acid.

SrCO₃(s) + 2HCl(aq) → SrCl₂(aq) + CO₂(g) + H₂O(l).

State the equation for the reaction of barium carbonate with hydrochloric acid.

BaCO₃(s) + 2HCl(aq) → BaCl₂(aq) + CO₂(g) + H₂O(l).

State the equation for the reaction of calcium oxide with nitric acid.

CaO(s) + 2HNO₃(aq) → Ca(NO₃)₂(aq) + H₂O(l).

State the equation for the reaction of magnesium with ethanoic acid.

Mg(s) + 2CH₃COOH(aq) → (CH₃COO)₂Mg(aq) + H₂(g).

Identify the oxidation and reduction when magnesium reacts with ethanoic acid.

Mg is oxidised: oxidation number increases from 0 to +2; H is reduced: oxidation number decreases from +1 to 0.

Draw a dot-and-cross diagram for CaBr₂ showing outer electrons only.

Ca: loses 2 electrons to become Ca²⁺ (no outer electrons shown); two Br atoms: each gains 1 electron to become Br⁻ with 8 electrons (7 crosses + 1 dot or vice versa); correct charges on both ions.

Draw a dot-and-cross diagram for Ca₃N₂ showing outer electrons only.

Three Ca²⁺ ions (each no outer electrons, charge 2+); two N³⁻ ions (each 8 outer electrons, charge 3-); correct charges on both ions.

Draw a dot-and-cross diagram for CaO showing the ionic bonding.

Ca²⁺ (no outer electrons); O²⁻ (8 outer electrons); correct charges.

Draw a dot-and-cross diagram for N₂O showing outer electrons only.

Linear molecule with N in centre; N≡N-O or N-N≡O; each N has 8 electrons; O has 8 electrons; correct bonding.

Draw a dot-and-cross diagram for BaO₂ showing outer shell electrons only.

Ba²⁺ (no outer electrons); [O-O]²⁻ (each O has 8 electrons with a single bond between them); correct charges.

Explain why Group 2 metals are referred to as reducing agents.

Group 2 elements lose 2 electrons (are oxidised themselves); they donate electrons to other species; they cause reduction of other species.

Explain why magnesium reacts with aqueous copper(II) sulfate in terms of electron transfer.

Mg atoms lose 2 electrons each (oxidised to Mg²⁺); Cu²⁺ ions gain 2 electrons each (reduced to Cu); Mg is the reducing agent; Cu²⁺ is the oxidising agent.

State the equation for the reaction of magnesium with aqueous copper(II) sulfate.

Mg(s) + CuSO₄(aq) → Cu(s) + MgSO₄(aq).

Explain why magnesium fizzes when added to water containing copper(II) sulfate.

The magnesium reacts with water in the mixture; Mg(s) + 2H₂O(l) → Mg(OH)₂(aq) + H₂(g).