Metals and Non-Metals - Important Points You Should Know
CBSE Class 10 - Chemistry
1. At present about 118 elements are known.
2. Elements can be divided into two main groups: metals and non-metals.
3. Elements which form positive ions by losing electrons are called metals. Thus, metals are the elements which have the tendency to lose electrons.
4. Metals are lustrous, ductile, malleable and good conductors of heat and electricity. They are solids at room temperature except for mercury which is a liquid.
5. Almost all the metals combine with oxygen (or air) to form metal oxides that are basic in nature except aluminium oxide and zinc oxide which are amphoteric in nature.
6. Metallic oxides are insoluble in water but some of them dissolve in water to form hydroxides known as alkalis.
7. Metals react with water and produce a metal hydroxide and hydrogen gas except for a few less reactive metals (such as Cu, Hg, Ag, Au, and Pt).
8. All metals react with dilute sulphuric acid, and hydrochloric acid to produce salt and hydrogen gas.
9. Aqua-regia is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in a ratio 3:1
10. Reactive metal can displace a comparatively less reactive meal from its compounds in an aqueous salt solution or in molten form.
11. Metals above hydrogen in the reactivity series can displace hydrogen from dilute acids.
12. Hydrogen also has non-metallic properties but, due to its electro-positive nature, it has been placed reactivity series.
13. Non-metals are those form which forms negative ions by gaining
14. Non-metals do not react with water or steam to evolve hydrogen gas.
15. Non-metals do not react with dilute acids to release hydrogen gas. They react with hydrogen to form hydrides.
16. Ionic compounds (like sodium chloride) do not exist as discrete molecules but they are the aggregates of oppositely charged particles.
17. The elements or compounds which occur naturally in the earth's crust are known as minerals.
18. Minerals from which metals can be extracted profitably are called ores.
19. Removal of unwanted material (gangue) from the ores called enrichment or concentration of ore.
20. The process of purification of the metal obtained after reduction is called the refining of metals.
21. Many metals like Cu, Sn, Ni, Ag, et, are refined electrolytically.
22. Corrosion is the slow process of eating away metals through the reaction of atmospheric air and moisture.
23. Rusting of iron is prevented by galvanising, making alloys, painting, greasing or oiling and tin-plating and chromium-plating.
24. An alloy is a homogeneous mixture of two or more metals or non-metals.
Ch 3 - Metals and Non-Metals (Q & A)
Ch3 - Uses of Some Common Metals and Non-Metals
Ch 3 - Metals vs Non-Metals (Comparison)
Ch 3 - Metals and Non-Metals - Alloys, Their Compositions, Properties and Uses
Ch 3 - Metals and Non-Metals (Short Q & A)
Ch 3 - Metals and Non-metals (Very Short Answer-Based Questions)
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