What are the properties of alkaline earth metals?

Alkaline earth metals are the elements of Group 2 in the periodic table (Be, Mg, Ca, Sr, Ba, Ra). They share several common physical and chemical properties:

General Properties of Alkaline Earth Metals

1. Position in Periodic Table
   • Found in Group 2.
   • Valence shell configuration: ns².
   • Examples: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra).

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Physical Properties

1. Appearance – Silvery-white, shiny metals.
2. Hardness – Harder than alkali metals but softer than most transition metals.
3. Density – Denser than alkali metals (except calcium, which is less dense than expected).
4. Melting & Boiling Points – Higher than alkali metals of the same period but decrease down the group.
5. Conductivity – Good conductors of heat and electricity due to metallic bonding.

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Chemical Properties

1. Reactivity – Less reactive than alkali metals but still highly reactive; reactivity increases down the group.
2. Oxidation State – Show a stable +2 oxidation state by losing two valence electrons.
3. Reaction with Oxygen – Form oxides (MO), which are basic in nature.
   • Example: 2Mg + O₂ → 2MgO
4. Reaction with Water –
   • Be: does not react with water.
   • Mg: reacts slowly with hot water.
   • Ca, Sr, Ba, Ra: react readily with cold water, releasing H₂ gas.
5. Reaction with Acids – React vigorously with dilute acids to form salts and release hydrogen gas.
   • Example: Mg + 2HCl → MgCl₂ + H₂↑
6. Reaction with Halogens – Combine directly to form ionic halides (MX₂).
7. Compounds – Their compounds (oxides, hydroxides, carbonates, sulfates) are generally ionic, white, and less soluble in water (solubility decreases down the group, except hydroxides, which become more soluble).

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Trends Down the Group

• Atomic & Ionic Size → Increases.
• Ionization Energy → Decreases.
• Electronegativity → Slightly decreases.
• Reactivity with water → Increases.
• Thermal stability of carbonates & nitrates → Increases down the group.

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In short: Alkaline earth metals are shiny, moderately reactive metals with +2 oxidation state, forming ionic, basic compounds. Reactivity and metallic character increase from Be to Ra.