3.2.2 Group 2, the Alkaline Earth Metals

Flashcards covering the properties, reactions, and uses of alkaline earth metals and their compounds.

Melting Point Trend in Group 2

Decreases down the group due to weaker metallic bonds as cation size increases.

Reason for Weaker Metallic Bonds Down Group 2

Larger cations result in a weaker electrostatic attraction between nuclei and delocalized electrons.

Extraction of Titanium with Carbon issue

Titanium carbide is brittle and useless

Titanium Extraction with Magnesium - Step 1

Heat titanium dioxide with carbon and chlorine to make TiCl24 and 2CO

Titanium Extraction with Magnesium - Step 2

Reduce with magnesium (magnesium donates electrons to titanium).

Role of Magnesium in Titanium Extraction

Reducing agent; donates electrons to titanium.

Uses of Calcium Compounds: Wet Scrubbing

Removes sulfur dioxide gas using CaO (quicklime) or CaCO3 (limestone).

Wet Scrubbing with CaO Result

Forms calcium sulfite (solid) which can be collected.

Wet Scrubbing with CaCO3 Result

Forms calcium sulfite and CO2.

Reaction of Group 2 Metals with Water

Metal X + H₂O -> X(OH)₂ + H₂

Reactivity Trend of Group 2 Metals with Water

Increases down the group.

Beryllium's Reactivity with Water

Does not react at room temperature.

Magnesium's Reactivity with Water

Reacts very slightly with water at room temperature but reacts rapidly with steam.

Quicklime Chemical Formula and State

CaO, solid

Limestone Chemical Formula and State

CaCO3, solid

Slaked Lime Chemical Formula and State

Ca(OH)2, solid

Limewater Chemical Formula and State

Ca(OH)2, aqueous

Solubility of Group 2 Hydroxides Trend

Increases down the group.

Observation of Magnesium Hydroxide

White precipitate due to low solubility.

Use of Magnesium Hydroxide

Aids digestion by balancing pH.

Safety of Magnesium Hydroxide

Low solubility means it's not strong enough to damage the body; pH doesn't rise too much because not many OH- ions are released.

Use of Calcium Hydroxide (Slaked Lime) in Agriculture

Neutralizes acidic soil.

Reason for Using Slaked Lime Over Magnesium Hydroxide in Agriculture

Calcium hydroxide is stronger/more soluble than magnesium hydroxide.

Solubility Trend of Group 2 Sulfates

Decreases going down the group.

Barium Sulfate's Solubility

Almost insoluble.

Use of Barium Sulfate in X-rays

Absorbs X-rays because barium is dense.

Safety of Barium Sulfate

Non-toxic because it is almost insoluble and won't be absorbed into the gut.

Use of Barium Chloride

Test for sulfate ions.

Reaction of Barium Chloride with Sulfate Ions

Forms barium sulfate, a white precipitate.

Interference in Sulfate Ion Test

Carbonates also form white precipitates with barium chloride.

Solution to Carbonate Interference

Add acid to react with carbonates and form CO2 (acidification).