PERIODIC TABLE CLASSIFICATION

PERIODIC TABLE CLASSIFICATION

Mrs .Sulekha Rani.R ,PGT Chemistry

A Brief History of the Periodic Table

MEMORIZE PERIODIC TABLE ELEMENTS 

Type of Organic Chemical Reactions

Type of organic Reactions 

By Sulekha Rani.R, PGT Chemistry

ADDITION REACTION

Oil to Ghee 

combustion reaction

CLEANING ACTION OF SOAP

   

CLEANING ACTION OF SOAP

Mrs Sulekha Rani R , PGT Chemistry

 

SOAP AND DETERGENT 

Questions from Chemical reactions (1)

Chemical Reaction : 
Sulekha Rani.R , PGT Chemistry , KV NTPC Kayamkulam 



Q.1.   A water insoluble substance ‗X‘ on reacting with dilute H2SO4 released a   colourless and  odourless gas accompanied by brisk effervescence. When the gas was passed through water, the solution obtained turned blue litmus red. On bubbling the gas through lime water, it initially became milky and milkyness disappeared when the gas was passed in excess. Identify the substance ‗X‘. Write its chemical equations of the reactions involved

Ans.    The water insoluble substance ‗X‘ is metal carbonate CaCO3.
                    CaCO3 (S) + H2SO4 (Aq) ............... CaSO4(Aq) + H2O (Aq) + CO2 (G)
                  Ca(OH)2 + CO2 (G).........................CaCO3 (S) + H2O (L)
                   (milky)
                CaCO3 (S) + CO2 (G)+ H2O (Aq)....................CaHCO3
               (milkiness)

Q.2. Ahmad took a magnesium ribbon (cleaned) and burned it on a flame. The 
        white powder formed was taken in a test tube and water was added to it. He 
        then tested the solution formed with red and blue litmus paper. What change 
         was seen? Why?
     Ans. Red litmus paper turned blue.
            Blue litmus paper remained blue.
     This is because the magnesium ribbon on burning in air forms the white 
        magnesium oxide. Which dissolved in water, it forms magnesium hydroxide, 
         which is Basic in nature.

Q.3. Give one example of a combination reaction in which an element combines 
         with a compound to give you a new compound.
              Ans.      O2 + 2SO2........ 2SO3
                             8NH3 + 3Cl2........... 6NH4Cl

Q.4. Marble statues often slowly get corroded when kept in open for a long time.  
        Assign a suitable explanation.

Q.5. Mohan tool pure water for the electrolytic decomposition of water but did not  
          see any bubbles  near the electrodes. Explain why?

Q. 6 Rancidity is a process used for spoiling of cooked food materials like 
        vegetables, etc. When kept for long time in open. How can you prevent such 
        process to proceed? Give an example.

Q. 7 A substance ‗X‘ displaces ‗Y‘ from its solution in water. It is called 
         displacement reaction. What other chemical name can be given to such type
         of reactions? Explain, giving an example?


Q. 8 Why is respiration considered an exothermic reaction? Explain.

Q. 9 Why is respiration considered an exothermic reaction? Explain.

Q. 10 Why are decomposition reactions called opposite of combination reactions? 
          Write equations for these reactions.

Q. 11  A shiny brown colored element ‗X‘ on heating in air becomes a black 
           coloured compound. Name the element ‗X‘& black the coloured compound 
           formed. Also write the equation

Dobereiner's Triads... Classification of elements

Dobereiner''s Triad- Law of Triads
Sulekha Rani.R,PGT Chemistry ,K V NTPC Kayamkulam

Johann Wolfgang Döbereiner (December 13, 1780 – March 24, 1849) was a German Chemist who is best known for work that foreshadowed the periodic law for the chemical elements.

In 1829, Dobereiner, a German scientist made

some groups of three elements each and called

them triads.

He observed that the atomic mass of the middle element of a triad was nearly equal to the arithmetic mean of

atomic masses of other two elements. All three elements of a triad were similar in their properties.

Let us take the example of three elements lithium, sodium and potassium. They form a Dobereiner’s triad.

Elements	Atomic mass
Lithium (Li)	7
Sodium (Na)	23
Potassium(K)	39

Mean of the atomic masses of the first (Li) and the third (K) elements: 7+39/ 2 = 23 u

The atomic mass of the middle element, sodium, Na =23 u

Other example..Triads.

Elements	Atomic mass
calcium(Ca)	40
barium(Ba)	88
Strontium(K)	137

Elements	Atomic mass
Chlorine	35.5
Bromine	80
Iodine	127

Mean of the atomic masses of the first and third elements =40+137/2 = 88.5 u= 88u

Mean of the first atomic masses of the and third elements =

35.5 +127/2 = 81.5 u= 80 u

Demerits:

Dobereneir’s idea of classification of elements into triads did not receive wide acceptance as he could arrange only a few elements in this manner.

Extra Information:

Döbereiner also is known for his discovery of furfural , for his work on the use of platinum as a catalyst, and for a lighter, known as Dobereiner's Lamp.

learn Symbols

Question 1 (15 points)
Match the symbols with the name

iron	KIFeBaSAuPZnSiPbClCuNaAgBr
silicon	KIFeBaSAuPZnSiPbClCuNaAgBr
lead	KIFeBaSAuPZnSiPbClCuNaAgBr
copper	KIFeBaSAuPZnSiPbClCuNaAgBr
zinc	KIFeBaSAuPZnSiPbClCuNaAgBr
sulfur	KIFeBaSAuPZnSiPbClCuNaAgBr
potassium	KIFeBaSAuPZnSiPbClCuNaAgBr
sodium	KIFeBaSAuPZnSiPbClCuNaAgBr
silver	KIFeBaSAuPZnSiPbClCuNaAgBr
gold	KIFeBaSAuPZnSiPbClCuNaAgBr
phosphorus	KIFeBaSAuPZnSiPbClCuNaAgBr
barium	KIFeBaSAuPZnSiPbClCuNaAgBr
bromine	KIFeBaSAuPZnSiPbClCuNaAgBr
iodine	KIFeBaSAuPZnSiPbClCuNaAgBr
chlorine	KIFeBaSAuPZnSiPbClCuNaAgBr

Class X - Chemistry Theory. Sample Question Paper 1

Class X Theory- chemistry.. Question Paper - 1

By Sulekha Rani.R, PGT Chemistry, KV NTPC Kayamkulam

1.

A Metal is treated with dil H₂SO₄ acid. The gas evolved is collected by the method shown in the figure. Answer the following

(1) Name the gas

(2) Name the method of collection

(3) Is the gas soluble or insoluble in water

(4) Is the gas lighter or heavier than air 2m

2. 2. Dry HCl gas does not turn blue litmus red where as hydrochloric acid does.Give one reason? 1m

3. Identify substance oxidised and reduced in the following reaction

MnO₂ + 4 HCl MnCl₂ + Cl₂ + 2H₂O 1m

4. A student dropped few pieces of marble in dilute hydrochloric acid contained in a test tube. The evolved gas was passed through lime water. What change would be observed in lime water? Write balanced chemical equation for both the changes occurred 3m

2. 5. Answer the following

(1) why is plaster of paris written as CaSO₄. ½ H₂O ? How is it possible to have half a water molecule attached to CaSO₄

(2) Why is NaHCO₃ an essential ingredient in antacids?

(3) When electricity is passed through an aqueous solution of sodium chloride three products are obtained. Why is the process called chlor alkali method ? 3m

6. Give reason

(a) During summer season milkman adds a very small amount of baking soda to fresh milk

(b) Potato chips manufacturers fill the packet of chips with nitrogen gas

(c) Tap water conduct electricity whereas distilled water does not.

(d) Water be never added to conc H₂SO₄

(e) Why copper vessels should not be used for keeping curd 5m.

7 . What will happen if a spoon of iron is used to stirring copper sulphate solution. 1m

8. What is amphoteric oxide ? give one example? Also write chemical equation. 2m

9. Why Plaster of Paris should be stored in moisture proof container? 1m

10. Write any 2 uses of the following

(1) NaHCO₃ (2) CaOCl₂ (3) NaOH (4) Plaster of paris