Group II - The Alkaline Earth Metals

Group II - The Alkaline Earth Metals

• Group II metals lose two electrons to form 2+ ions when they react, achieving a full outer shell.

Atomic Radius

• Atomic radius of Group II metals increases down the group due to additional electron shells.

Reactivity

• Increased electron shielding down the group makes outer electrons easier to lose.
• Reactivity of Group II metals increases down the group.

Ionisation Energy

• First ionisation energy of Group II metals decreases down the group due to a greater atomic radius and increased shielding.

Melting Point

• Group II elements are metallic, meaning larger ions within the metallic structure have weaker attractive forces.
• Melting points decrease down the group due to the attractive force having to act over a greater distance.

Reactions with Water

• Group II metals react with water in a redox reaction to produce a metal hydroxide and hydrogen.
• Metal hydroxide forms as an alkaline solution, hence the group being known as the alkali metals.
• Magnesium reacts slowly with liquid water, but faster with steam, producing a bright white flame and forming hydrogen and magnesium oxide.

Solubility of Hydroxides

• Solubility of Group II hydroxides increases down the group, with magnesium hydroxide being the least soluble and barium hydroxide being the most soluble.
• Magnesium hydroxide is used in medicine as an antacid and in agriculture to neutralise acidic soils.

Solubility of Sulfates

• Group II sulfates decrease in solubility down the group, with magnesium sulfate being the most soluble and barium sulfate being the least soluble.
• Insolubility of barium sulfate makes it useful in medicine as barium meals, allowing internal tissues and organs to be imaged.
• Barium sulfate is toxic if it enters the bloodstream, but its insolubility makes it safe to use in medicine.
• Barium chloride is used as a test for sulfate ions, reacting to form barium sulfate, which forms a white precipitate when sulfate ions are present.

Metal Extraction

• Magnesium is used in the extraction of titanium from titanium chloride via a displacement reaction.

Flue Gas Removal

• Calcium oxide reacts with sulfur dioxide to remove it from factory pollutants and prevent its release into the atmosphere, forming calcium sulfite and water.