Group 2 (Alkaline Earth Metals) Review

18 question-and-answer flashcards covering properties, trends, reactions and applications of Group 2 alkaline earth metals.

Which elements belong to Group 2, also called the alkaline earth metals?

Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba) and Radium (Ra).

What block of the periodic table do Group 2 elements occupy?

They are s-block elements.

What is the general outer-electron configuration of a Group 2 element?

[noble gas] ns² (two electrons in the outermost s-orbital).

Give two key physical properties common to Group 2 metals.

They are shiny, silvery-white, conduct electricity, and have relatively high melting/boiling points while being harder and denser than Group 1 metals.

How does atomic radius change down Group 2 and why?

Atomic radius increases because additional electron shells create greater shielding that outweighs the higher nuclear charge.

What is the trend in first ionisation energy down Group 2?

Ionisation energy decreases because outer electrons are farther from the nucleus and more shielded, so attraction is weaker.

How does reactivity change down Group 2 and what causes this trend?

Reactivity increases down the group; lower ionisation energy makes it easier for the metals to lose their two outer electrons.

Write the general equation for the reaction of a Group 2 metal (M) with oxygen.

2 M + O₂ → 2 MO (a white, basic oxide forms).

What products form when a Group 2 metal reacts with water, and how does reaction speed vary down the group?

M + 2 H₂O → M(OH)₂ + H₂; the reaction becomes faster from Mg (slow in cold water) to Ba (vigorous).

Describe the solubility trend of Group 2 hydroxides down the group.

Solubility increases: Mg(OH)₂ is sparingly soluble, Ca(OH)₂ slightly soluble, Sr(OH)₂ and Ba(OH)₂ increasingly soluble (Ba(OH)₂ gives a strong alkali).

Describe the solubility trend of Group 2 sulfates down the group.

Solubility decreases: MgSO₄ is very soluble, CaSO₄ slightly soluble, BaSO₄ practically insoluble.

Why is BaSO₄ useful as a ‘barium meal’ in medical imaging?

Its very low solubility makes it non-toxic while opaque to X-rays, allowing clear imaging of the gut.

Outline the laboratory test for sulfate ions using a Group 2 compound.

Add HCl to remove carbonates, then BaCl₂(aq); a white BaSO₄ precipitate confirms SO₄²⁻ presence.

State one agricultural use of calcium hydroxide, Ca(OH)₂.

It neutralises acidic soils (Ca(OH)₂ + 2 H⁺ → Ca²⁺ + 2 H₂O).

State one medicinal use of magnesium hydroxide, Mg(OH)₂.

It acts as an antacid, neutralising excess stomach acid (Mg(OH)₂ + 2 HCl → MgCl₂ + 2 H₂O).

How does the thermal stability of Group 2 carbonates change down the group?

Thermal stability increases; higher temperatures are required to decompose MCO₃ into MO + CO₂.

Explain why carbonate thermal stability increases down Group 2.

Larger cations have lower charge density, polarise the carbonate ion less, so more heat is needed to decompose it.

Summarise five key trends down Group 2 (atomic radius, ionisation energy, water reactivity, hydroxide solubility, sulfate solubility).

Atomic radius ↑, first ionisation energy ↓, reactivity with water ↑, hydroxide solubility ↑, sulfate solubility ↓.