Important Points of Metals and Non metals

Important Points of Metals and Non metals

  • Metals are lustrous, malleable, ductile and have high density.
  • Metals are generally good conductors of heat and electricity.
  • Metals form positive ions by losing electrons.
  • All metals combine with oxygen to form metal oxides.
  • Metal oxides are basic in nature.
  • Metals react with chlorine to form electrovalent chlorides of metals.
  • Metals like Li, Na and Ca form hydrides with hydrogen.
  • There are metal-bearing substances below the earth’s surface which are called minerals.
  • The minerals from which metals can be obtained profitably are called ores.
  • A flux is a substance which is added to the furnace charge to remove nonfusible impurities present in the ore.
  • Flux combines with the nonfusible impurity to convert it into a fusible substance known as slag.
  • Nonmetals are generally bad conductors of heat and electricity.
  • All nonmetals are electronegative.
  • The function of limestone in the extraction of iron is to provide calcium oxide (CaO) for the formation of the slag CaSiO3.
  • Alloy steels are prepared by adding a small quantity of nickel, cobalt, chromium, tungsten, molybdenum, manganese or silicon to steel.
  • The heating of steel to redness and then cooling it slowly is called tempering of steel.
  • Rusting of iron is an oxidation reaction which occurs in the presence of air and water.
  • Aluminium is the most abundant metal in the earth’s crust.
  • The process of extracting metals from their ores and refining them for use is called metallurgy.
  • The unwanted materials present in an ore are called gangue.
  • Froth floatation is a method used for the concentration of some ores.
  • Calcination is the process of heating an ore strongly so that volatile impurities are removed.
  • Roasting is the process of heating an ore in a controlled supply of air at a controlled temperature.
  • Smelting is the process of obtaining metals from their compounds.
  • Bauxite is an ore from which aluminium metal is commercially obtained.
  • The most important are of aluminium is bauxite (Al2O3 × 2H2O).
  • Slow destruction of metals by the action of air, carbon dioxide, moisture, etc., is known as corrosion of metals.
  • An alloy consists of two or more metals, or a metal and a nonmetal. Brass is an alloy of copper and zinc.
  • The property of an element to exist in two or more ,… different forms is known as allotropy.
  • The most important ore of copper is copper pyrite (CuFeS2).
  • Copper when heated in air at 300°C forms cupric oxide (CuO), while at 1000°C forms cuprous oxide (Cu2O).
  • Silver does not react with water and hydrochloric acid. It, however, reacts with nitric acid to produce NO2 gas.
  • Gold dissolves in aqua regia. Aqua regia is a mixture of conc. hydrochloric acid and conc. nitric acid in the volume ratio 3 : 1.
  • Lead on rubbing leaves a mark on paper. Lead is the poorest conductor of heat.
  • Zinc when heated with a concentrated solution of sodium hydroxide gives off hydrogen gas, while sodium zincate is left in solution.
  • Sulphur is used in vulcanization of rubber.