3.2.2 Group 2

Trend in atomic radius:

Increases down group 2 due to sheilding

Trend in Ionic attraction:

Decreases down group 2 due to larger distance from nucleus to valence electrons

Trends in melting point:

Decreases due to larger cations electrostatic attraction between delocalised electrons decrease

Trend in Reactivity:

Decreases due to two outer electrons being lost more easily

Trend in ionisation energy:

Decreases as outer most electron can be removed more easily

Reactions with other substances:

Metal + oxygen → metal oxide

Metal + water → metal hydroxide + hydrogen

Metal + acid → salt + hydrogen

Properties of oxides:

Ionic except for BeO

Properties of hydroxides:

• More basic down the group

• Solubility increases due to less attraction to the OH^- ion

Properties of sulphates:

• White solid

• Solubility decreases down the group

  • Cations are less attracted to water

Properties of carbonates:

• Insoluble in water

• Thermal decomposition to form

• oxide + CO₂

What is magnesium hydroxide used for?

• In medicine for digestive upset

• Neutralises HCl in the stomach acid to create a neutral solution

What is the use of calcium hydroxide?

• Agriculture to neutralise acidic soils

• Ca(OH)2 + 2HNO3 →→ Ca(NO3)2 + 2H2O

What is the use of barium sulfate?

• Used for X-rays of the digestive system

• It is insoluble so doesn't dissolve in digestive track

• Absorbs X-rays

• Produces an image showing abnormalities

Magnesium reaction with steam vs cold water

Steam: MgO + H₂

Cold water: Mg(OH)₂ + H₂