Classification of Metal and Non-Metal

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1 1.1 2 1.2 Classification of Metal and Non-metal 1.2.1 Classifications Element can be divided into two classifications, metals and non-metals. main Table 1 Properties of metals and non-metals Properties Metal Non-metal State at room temperature and pressure Solids (except Mercury) Gas or Solid, Liquid (Bromine) Melting point and boiling point High Low (except diamond and graphite) Shiny Dull Electrical conductivity Good conductor Insulator (except Graphite) Heat conductivity Good conductor Insulator Ductile, malleable Brittle Appearance Flexibility 3 1.2 Classification of Metal and Non-metal 1.2.2 Metalloids Some elements have physical properties in between those of metals and non-metals. These elements are called semi-metals (metalloids). [An element that has both metallic and nonmetallic properties, as arsenic, silicon, or boron; or nonmetal that in combination with a metal forms an alloy.] The electro-negativities and ionization energies of the metalloids are between those of the metals and nonmetals, so the metalloids exhibit characteristics of both classes. They can conduct electricity, but poor than the conductivity of metals. For examples, Silicon (Si) has a metallic luster but is brittle in As semi-conductors nature. 4 1.2 Classification of Metal and Non-metal 1.2.3 Reactivity of Metals and Non-metals There is one chemical criterion which distinguishes the two classes. On reaction with oxygen a metal produces an oxide or a base. Conversely, non-metals give rise to acidic oxides – these neutralize alkalis or bases and turn litmus red. Metal oxide + water → metal hydroxide Non-Metal oxide + water → Acid e.g. CaO(s) + H2O(l) → Ca(OH)2(aq) SO3(g) + H2O(l) → H2SO4(aq) Neutralization Salt CaSO4(s) 5 1.2 Classification

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