BASIC CONCEPTS IN CHEMISTRY FOR CLASS X students

ELEMENT - ATOMIC NUMBER AND ITS SYMBOL

 Sulekha Rani.R, PGT Chemistry.

ELEMENT	ATOMIC NUMBER	SYMBOL
HYDROGEN	1	H
HELIUM	2	He
LITHIUM	3	Li
BERYLLIUM	4	Be
BORON	5	B
CARBON	6	C
NITROGEN	7	N
OXYGEN	8	O
FLUORINE	9	Fl
NEON	10	Ne
SODIUM	11	Na
MAGNESIUM	12	Mg
ALUMINIUM	13	Al
SILICON	14	Si
PHOSPHORUS	15	P
SULPHUR	16	S
CHLORINE	17	Cl
ARGON	18	Ar
POTASSIUM	19	K
CALCIUM	20	Ca

         

ELEMENT	SYMBOL
IRON	Fe
NICKEL	Ni
COPPER	Cu
ZINC	Zn
SILVER	Ag
GOLD	Au
TIN	Sn
LEAD	Pb
BROMINE	Br
IODINE	I
PLATINUM	Pt
MERCURY	Hg
BARIUM	Ba
MANGANESE	Mn
CHROMIUM	Cr
COBALT	Co

SYMBOL OF IONS

     Phosphate  PO₄^3-

     Sulphate  SO₄^2-

    

COMBINATION REACTION

TYPE OF CHEMICAL REACTIONS 

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

Type of Chemical Reactions 

1. Combination

1. Combination reaction 

     

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.