CBSC Science

  Metals and Non- Metals full explaination Class 10 Science Chapter 3 - Metals and non metals Element: Is a substance that can’t be broken into more simpler substances. Elements are classified into different categories: -: Metals :- Metals Metals are those elements which have 1,2 or 3 valence electrons in their valence shell. Example : atomic no. of Na =11 Electronic confugration =2,8,1 They always loose electrons to form electropositive ions. Na – 1electron ------Na + :-  Non Metals :- Non-Metals -> Non metals are those elements which have 4,5,6 or 7 valence electrons in their valence shell and they always gain electrons to form electronegative ions. Cl(17) – 1 electron --------Cl- Electronic Configuration = 2,8,7 Video Explanation of Lesson Metals and Non-Metals II)  Physical Properties Of Metals and Non Metals 1. malleability: process of beating into thin sheets Metals :are malleable. Gold and silver is the most malleable metals. Malleability Non metals :non malle...

Acid-bases and salts * Preparation and uses of important compounds. I) Caustic Soda (Sodium Hydroxide, NaOH) Preparation of Sodium hydroxide Preparation: In the process of electrolytic decomposition of brine (aqueous solution of sodium chloride), brine decomposes to form sodium hydroxide. 2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(g) + H2(g) In this process, chlorine is moved towards anode and hydrogen gas is moved towards cathode as by products. This whole process is known as Chlor – Alkali process. Uses: Sodium hydroxide is used for degreasing of metals, manufacturing of paper, soap, detergents, artificial fibres, etc. II) Bleaching Powder (Calcium Oxychloride, CaOCl2) Preparation of Bleaching powder Preparation: Bleaching powder is produced by the action of chlorine on dry slaked lime [Ca(OH)2]. Ca(OH)2 + Cl2→ CaOCl2 + H2O Uses: (i) It is use for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry; (i...

  • Importance of pH in everyday life :- --------------------------------------- I) Are plants and animals pH sensitive ?   -> Our body works within the pH range of 7.0 to 7.8 .  -> Organisms survive in this narrow pH range change.  -> When pH of rain water is less than 5.6 then it is called acid rain . It lowers the pH of river water when mix with it and the survival of aquatic life becomes difficult. II) pH of Soil :- pH of Soil   -> plants required a specific pH for their healthy growth.  -> In most plants, the optimum pH range is from 5.5 to 7.0 , but some plants will grow in more acid soil or may require a more alkaline level.   III) pH in our digestive system :- pH of digestive system   -> Our stomach produces hydrochloric acid which helps in the digestion of food without harming the stomach.   -> During indigestion stomach produces too much acid which causes pain and irritation . To get ride from thi...

 I) What happens to an Acid  in a Water Solution ? ->  The hydrogen ion produced in the presence of water in HCl. - >The separation of H+ ion from HCl molecules cannot occur in the absence of water.   HCl + H2O --------> H3O+  + Cl- - >Hydrogen ions cannot exist alone but exist after combines water molecules hence H+ (aq) or hydronium ion (H3O+) .   H+ + H2O --------> H3O+ II) What happens to an Base in a Water Solution ? - >Bases generate hydroxide (OH-) ions in water.  Bases which soluble in water are called alkalis .   Examples:-   a) NaOH(s) + H2O(l) --------> Na+(aq) + OH-(aq)  b) KOH(s) + H2O (l) ----------> K+ (aq) + OH- (aq)  c)  Mg(OH)2 (s) + H2O (l) ----------> Mg2+(aq) +2OH- (aq) III) Process of mixing of Acid or a Base with Water. - >The process of dissolving an acid or a base in water is a exothermic process .  - >We must take care when doing this process. Like mixing of c...

  I) Acids and Bases reacts with each other. - > When Acids reacts with Bases to form Salt and water as product. This reaction is also called as neutralisation reaction . Acid + Base ---------> Salt + Water  Example:- i) NaOH (aq) + HCl (aq) ---------> NaCl (aq) + H2O(l) ii) MgOH (aq) + HCl (aq) -------> Mg(OH)2 (aq) + H2O (l) iii) LiOH (aq) + HCl (aq) ---------> LiCl (aq) + H2O (l) iv) Ca(OH)2 (aq) + H2SO4 (aq) ---------> CaSO4 (aq) + H2O (l) II) Metallic Oxides reacts with Acids:- - > When Metallic Oxides reacts with Acids it gives Salt and Water as products. Metallic Oxide + Acid ------> Salt + Water Example :-  i)  CuO (s) + HCl (aq) -------> CuCl2 (aq) + H2O (aq) black colour                     blue-green colour ->We notice that tht the colour of the solution becomes blue-green due to the formation of copper(II) chloride in the reaction . ii) CuO (s) + H2SO4 (aq) -------> CuSO4 ...

                             • When Acids reacts with Metal.  ->  Acid + Metal ---------> Salt + Hydrogen gas. -> When Acids react with Metals it gives salt and liberate hydrogen gas. Example:- i) 2HCl (l)+ 2Na(s) ---------> 2NaCl(s)+ H2(g) ii) H2SO4 (l) + Mg (s) ----------> MgSO4(s) + H2 (g)  iii) 2CH3COOH (l) + 2Na(s) -------> 2CH3COONa (s) + H2 (g) • When Bases reacts with Metals: -> When bases reacts with metals it gives salt and Hydrogen gas . Base + Metal ---------> Salt + Hydrogen gas Example:-  I) 2NaOH (aq) + Zn (s) ----------> Na2ZnO2 (s) + H2 (s) II) NaOH (aq) + Al (s)  ----------> NaAlO2 + H2 (s) • Metal carbonate and metal hydrogen carbonate reacts with acids. -> When Metal carbonate/ Metal hydrogen carbonate reacts with acids to give Salt, Water and  releases Carbon dioxide gas. Metal carbonate/Metal hydrogen carbonate + Acid ------> ...

  Indicators :- • These are the substances which predict the solution acid or base by change its colour or odour . Types :- •Indicators are of two types:- 1) Natural indicators. 2) Synthetic indicators. 3) Olfactory indicators. 1) Natural indicators :- • These are indicators which are obtain from nature and predict the nature of solution. Example:- Litmus paper( it changes its colour in acidic and in basic solution), extract of hebiscus flower, red cabbage etc. 2) Synthetic indicators: - • These are the substances which are synthesised in lab or man mad indicators which predict the nature of solution by change in colour . Example :- phenolphthalein ( in acidic it's colourless and in basic its colour change to pink), Methylorange ( in acidic it's red and in basic its yellow) 3) Olfactory indicators :- These are the inductors which change its odour in acidic and in basic medium. Example:- Clove oil, Onion extract, vanilla etc. #Youtube chennel link :- https://youtu.be/LoIbygPU...

  Acids:- Acids are sour in taste. Acids contain H+ ions. Acids turns blue litmus paper to red. Example:- HCl, H2SO4, CH3COOH etc. Bases:- Bases are bitter in taste. Bases contain OH- ions. Bases turns red litmus paper to blue. Example:- NaOH, KOH, MgOH. Salts:- Salts are salty in taste. Salts doesn't contain H+ or OH- ions but when they desociate they gives A+ and B- ions. Example:- NaCl as Na+ , Cl- ions. Salts doesn't change in litmus paper( it remains same ). #Youtube chennel link :- https://youtu.be/LoIbygPUZPA