Chemistry Chapter 2 | 2nd Year

 Chapter 2 Notes | Chemistry 2nd Year

“S-Block Elements”

1. The elements of group IA except hydrogen are called ‘alkali metals’ while those group IIA are named as alkaline-earth metals.
2. Alkali metals have only one electron in s-orbital of their valence shell. They lose one electron of the valine shell forming monovalent positive ions.
3. Alkaline-earth metals have two electrons in s-orbital of their valence shell. They lose two electrons forming dispositive ions
4. Spodumene, chile salpetre, trona, borax, carnallite, sylvite, alunite, halite, natron are the common minerals of alkali metals.
5. Beryl, magnesite, dolomite, Epsom salt, asbestos, calcite, gypsum, strontionite and barite are the important minerals of alkaline-earth metals.
6. Lithium behaves different from the other alkali metals.
7. Lithium forms only normal oxide, whereas the others from higher oxides like peroxides and superoxide.
8. Beryllium is the only member of group II, which reacts with alkalis to give hydrogen. The other member do not react with alkalis.
9. Nitrates of lithium, magnesium and barium in heating give oxygen, nitrogen peroxide and the corresponding metallic oxides.
10. Sodium is prepared by the electrolysis molten sodium chloride in down’s cell.
11. Calcium is necessary for development of leaves ad it tends to accumulate in leaves and bark. An adequate quantity of calcium is essential for the optimum activity of microorganisms that produce nitrates.
12. Lime is used in paper and glass industries. It also used for refining sugar and other food products.

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