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Monday, 30 November 2015

10th Class- Metals and Non-Metals Part- 1

10th Class Chapter- Metals and Non-Metals


            Metals are the solid materials which are typically hard, malleable, ductile and conduct heat and electricity, and also posses metallic lusture.
Example- Iron, Gold, Aluminium, Silver, Copper etc.


                    Nonmetals are chemical elements which lacks metallic properties. Non metals are either solids or gases except Bromine (Br2), which occurs as liquid. Non-metals vaporizes easily, insulator of heat and electricity. Non metals have high ionization energy and elctronegativity values. 
Example- Hydrogen, Helium, Nitrogen, O2, F2, Ne, Cl, Ar, Kr, Xe, Rn, Br, C, P, S, Se, I.

Exception in metals and non-metals

·       Mercury is liquid at room temperature while other metals are solid.
·       Gallium and cesium have very low M.P. while other metals have very high M.P.
·       Iodine is non-metal but it has lusture (shiny).
·       Carbon (Non-Metal) exist in different forms, and these forms are known as allotrope.
·       Graphite (allotrope of carbon) conduct electricity and Diamond (allotrope of carbon) having very high M.P. and B.P. is hardest natural substance known.

Chemical properties of metal

Burning of metals in air

                                      Metals burn in air ( as oxygen present in air) to produce metal oxide.
Metal + Oxygen -------> Metal Oxide
Example- 2Cu (Copper) + O2 (air) ---> 2CuO (Copper Oxide)
                4Al (Aluminium) + 3O2 -------> 2Al2O3 (Aluminium Oxide)
·       Mostly metal oxide are basic in nature but some metal oxide are amphoteric in nature i.e. they show acidic as well as basic behavior like Aluminium Oxide, Zinc Oxide.
Al2O3 + 6HCl -------> 2AlCl3 + 3H2O
    Al2O3 + 2NaOH ----> 2NaAlO2 (Sodium Aluminate) + H2O
·       Mostly metal oxide do not dissolve in water but some dissolve to form alkali.
Na2O (s) + H2O (l) ---------> 2NaOH (aq)
K2O (s) + H2O (l) ---------> 2KOH (aq)
·       Some metals prevent further corrosion by making protective oxide layer on itself like Al, Zn, Pb etc.
·       Some metals like Na, K catches accidental fire so to prevent it, they are kept fully immersed in kerosene oil.

Reaction of metals with water

                                                 Most metal react with water to form metal oxide and hydrogen gas.
Metal + Water -----> Metal Oxide + Hydrogen Gas
2K (s) + H2O (l) -------> K2O (s) + H2 (g)
Not all, but some metal oxide react further with water to give metal hydroxide.
K2O (s) + H2O (l) -----> 2KOH (aq)
Some metal do not react with water like copper, lead, silver and gold.

Reaction of metals with acids

                                                 Most metal react with acids to produce salt and hydrogen gas.
Metal + Diluted Acid --------> Salt + Hydrogen Gas
2Al + 6HCl (dil) ---------> 2AlCl3 + 3H2
·       As HNO3 is strong oxidizing agent so, hydrogen gas not evolve when reaction take place between metal and nitric acid Because HNO3 reduces itself to nitrogen oxides (N2O, NO, and NO2).
·       Aqua-Regia (Royal Water) is freshly prepared mixture of concentrated Hydrochloric Acid (Conc. HCl) and concentrated Nitric Acid (Conc. HNO3) in the ratio of 3:1.
Aqua Regia have great dissolving power, highly corrosive, fuming liquids. Aqua Regia have ability to dissolve gold and platinum.

Reaction of metals with solution of other metal salts

                                                                                    More reactive metal have ability to displace less reactive metal from their compounds in molten or solution form.
For example, If metal A is more reactive then metal B then it displaces metal B from solution of metal B.
Metal A + Salt Solution of B ------> Salt Solution of A + Metal B

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