General Characteristics of Compounds of Alkaline Earth Metals
Table of Content
- Define Alkaline Earth Metals
- General Characteristics of Compounds of Alkaline Earth Metals
- Uses of Alkaline Earth Metals
Group 2 elements are known as Alkaline Earth Metals. It includes beryllium, magnesium, calcium, strontium, barium, and radium. They exist in +2 oxidation states.
The general outer electronic configuration of alkaline earth metal is ns2.
Fig. 1. Electronic configuration of alkaline earth metals
- They are silvery, white, and hard metals. They are softer but harder than alkali metals.
- Some appears white but beryllium and magnesium appear greyish.
- Their melting and boiling points are higher compared to alkali metals.
- They are strongly electropositive in nature. Alkaline earth metals give different color with flame test such as calcium gives brick red color, strontium gives crimson color and barium gives apple green color.
- All alkaline earth metals forms monoxide except beryllium.
- They have high electrical and thermal conductivities as they have metallic bonding.
- The oxides of alkaline earth metals are basic but less basic than alkali metals.
- Hydroxides of alkaline earth metals are basic in nature except beryllium hydroxide.
- Group 2 metals forms solid carbonates. As one moves from beryllium to barium thermal stability of carbonates increases.
- Alkaline earth metals also form sulphates such as BeSO4, and MgSO4. Beryllium sulphate and magnesium suphate is soluble in water as compared to other suphates of alkaline earth metals.
- Group 2 elements form hydrated, crystallized nitrates. Heating of nitrates form oxides, Barium nitrate crystallizes to form anhydrous salt whereas magnesium nitrate crystallizes with six molecules of water.
2Ba(NO3)2 + heat → 2BaO + 4NO2 + O2
- Alkaline earth metals forms halides after reacting with halogens. Beryllium chloride polymerizes in solid phase.
Fig. 2. Polymerization in beryllium chloride
There is a formation of coordinate bond between beryllium and chloride. Halides of beryllium are covalent. But halides of calcium, barium and strontium are ionic or electrovalent in nature.
Fig. 3. Halides of alkaline earth metals
- They are used for the alloy formation.
- Beryllium is used for manufacturing of windows of X-ray tubes.
- Magnesium-aluminum alloys are used for air craft construction.
- Toothpaste contains magnesium carbonate
- Calcium is used in the extraction of metals from oxides.
- Calcium is a major component of bones and teeth.
- Radium is used in radiotherapy, such as, in the treatment of cancer.
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