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www.ncerthelp.com CHAPTER 3 METALS AND NON METALS GIST OF THE LESSON Elements are classified broadly into two categories on the basis of properties: Metals: Iron, Zinc, Copper, Aluminium etc. Non metals: Chlorine, Nitrogen, Hydrogen, Oxygen, Sulphur etc. Apart from metals and non-metals some elements show properties of both metals and non metals, e.g. Silicon, Arsenic, Germanium .They are called metalloids Comparison of physical and chemical properties of metals and non metals:Sr. Property Metals Non-Metals No. 1 Physical Metals are solid at room Non-metals generally State temperature. Except exist as solids and mercury and gallium. gases, except Bromine. 2 Melting and Metals generally have Non-metals have low boiling high m.pt and b.pt m.pt and b.pt except points except gallium and diamond and graphite. cesium. 3 Density Generally high. Generally low. 4 Malleability Malleable and ductile. Neither malleable nor and ductile. Ductility 5 Electrical Good conductors of heat Generally poor and thermal and electricity. conductors of heat and conductivity electricity except graphite. 6 Luster Poses shining luster. Do not have luster except iodine. 7 Sonorous Give sonorous sound Does not give sound when struck. sonorous sound. 8 Hardness Generally hard except Solid non-metals are Na, K generally soft except diamond. 24 Visit www.ncerthelp.com for Ncert Solutions in Text and Video , CBSE Sample papers, Exam tips, NCERT BOOKS, Motivational Videos, Notes for All Classes and Many More...
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