Thursday, May 18, 2017

CBSE Class 8/10 - Metals vs Non-Metals (Comparison) (#cbseNotes)

Metals vs Non-Metals

Physical Properties Comparison

Property Metals Non Metals
Physical State Most metals are solids at room temperature except mercury which is a liquid. Gallium and Cesium also changes into liquid at slightly above room temperature. Non Metals exist in all states. Eleven are gases, bromine is liquid while others are solids.
Melting and Boiling Point Generally have high melting and boiling points. (Exceptions are Gallium, Mercury, Sodium and Potassium.) Generally they have low melting and boiling points. Exceptions are: Carbon, Boron and Silicon.
Density They have high density except Sodium and potassium. Low denisty (Diamond is an exception.)
Lusture Metals shine and are lustrous. Non-metalls appear dull. (Exceptions are Diamond, graphite and iodine.)
Hardness Generally hard and have high tensile strength. Sodium and Potassium are exceptions which can be cut by a knife. Some are soft (e.g. Sulphur and Phosphorius), while some are hard. Diaomond (carbon) is one of the hardest substance.
Brittleness Metals are hard but not brittle. (Exception: Zinc) Non-Metals, generally, are brittle
Tensile Strength In general metals have high tensile strength and can bear haevy load. (Exceptions are Mercury, Sodium, Potassium, Gallium etc.) Long tensil strength except carbon fibres.
Malleability Metals are usually malleabile i.e. can be beaten into thin sheets. (Exceptions are Mercury and Zinc). Gold and Silver are highly malleable. They are non-malleable.
Ductility Metals can be drawn into thin wires (exceptions are zinc, mercury and gallium). Non-Metals are non-ductile (except carbon fibres, plastic sulphur).
Alloys They form alloys. Non-Metals do not form alloys.
Thermal and Electrical Conductivity Good conductor of heat and electricity. (Except Tungsten). Copper and Silver are very good conductors. Generally poor conductors (exception is graphite)
Solubility Metals generally are not soluble in solvents (water, alcohol etc.) Non-metals dissolve in solvents. e.g. iodine dissolves in carbon disulpide and chloroform. Sulphur disssolves in carbon disulphide.
Sonorus Metals are sonorous. They are non-sonorous.

Chemical Properties Comparison

Charge Electropositive in nature i.e. gain +ve charge by losing electrons. Electronegative in nature i.e. get -ve charge by gaining electrons.
Reaction with oxygen Form basic oxides e.g. Na₂O, MgO and Al₂O₃ Form acidic oxides e.g. CO₂, SO₂ and P₂O₅. Neutral Oxides are H₂O, CO and NO.
React with Acids Displaces Hydurogen and form metal salt and H₂ gas is released. Non-metals do not react with dilute acids and do not evolve H₂ gas.
React with Water Metals react with water and form oxides. H₂ gas is evolved. Metals do not react with water. H₂ gas does not evolve.
Oxides with Water Metal oxides (basic oxides) react with water and form bases or alkalis.Na₂O + H₂O ---> 2NaOH Oxides of non-metals are acidic and form acids when react with water.
CO₂ + H₂O ---> H₂CO₃ (carbonic acid)
Reaction with Hydrogen Metals do not react with H₂. Exception: Certain metals Na, Li, Ca, Be etc. combine with H₂ and form unstable hydrides. Non-metals combne with hydrogen and form stable hydrides.

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