Introduction of periodic table

·       Total number of elements in periodic table are 118

·       18 groups in periodic table.

·       7 periods in periodic table.

·       18thgroup called noble or inert gas family.

·       17th group is called halogen family.

·       14th group is called carbon family.

·       First group is called alkali metal group.

·       Second group is called alkali earth metal group.

·       d block elements of periodic table are also called transitional element that have more than one valency Such as Cu+ & Cu2+, Fe2+& Fe3+

PERIODIC TABLE

Those elements which have 3 valence electron in their outermost shell will be member of 13th group.

Some extra valency

·         Ag +1= silver

·         Ca2+= Calcium

·         Br+1 = Bromine

·         Ba2+= Barium

·         Cl-1= Chlorine

·         SO42- =Sulphate

·         CO32- = Carbonate

·         NO3-1 = Nitrate

·         OH-1 = Hydroxide

·         Cu2+ = Copper cupric

·         Pb2+ = lead

·         NH4+1 = Ammonium

·         Cu+1 = Cuprous copper

·         PO43- = Phosphate

·         NO2-1= Nitrite

·         N3- = Nitride

·         Zn2+= Zinc

·         K+ = Potassium

·         Hg2+= Mercurous mercury

·         Sr2+= Strontium

·         CaO= Quick lime

·         CaCO3= lime stone

·         Ca(OH)2 = Slaked lime

Colour of some compound

·         CuO = Copper oxide = black

·         Cu = Copper = red brown

·         PbI2 = lead iodide = yellow ppt

·         Al(OH)3 = Aluminum hydroxide = white ppt

·         CuS = Copper Sulphate = black ppt

·         BaSO4 = Barium Sulphate = white ppt

·         AgCl= silver chloride = white ppt

·         CuNO3 = copper nitrate = blue solution

·         AgNO3 = Silver nitrate = Colorless

·         CuCl2 = copper chloride = green Colour

·         ZnSO4 = Zinc Sulphate = colorless

·         FeSO4 = Ferrous Sulphate = green solution

·         CuSO4 = Copper Sulphate = blue solution

·         AgCl = Silver chloride = white

·         Ag = silver = grey

·         PbO = lead oxide = yellow Colour

·         Fe2O3 = Ferric oxide = brown Colour

·         NO2 = nitrogen dioxide = brown fumes

·         CaCO3 = calcium carbonate = white

CHEMICAL REACTION

The process in which new substance are formed due to rearrangement of atoms between reactants

·         The substance which take part in a chemical reaction are called reactants

·         The new substances which produced as result of chemical reaction are called as products

Example: N2 + O2 NO KClO3 MnO2 KCl + O2

Magnesium is silvery white metal mg metals is available in a science laboratory in the form of magnesium ribbon or say magnesium wire. When a magnesium ribbon is heated it burns in air with a dazzling white flame to form a white powder called as magnesium powder MgO on heating magnesium combine with oxygen present in air to form MgO.

Mg + O2 MgO

Magnesium ribbon which we use has a coating of magnesium carbonate possibly of oxide on its surface that is formed by slow action of moist air on it so before burning magnesium ribbon is cleaned by rubbing with a send paper to remove carbonate layer from its surface

 Characteristics of chemical reactions

1.     An evolution of gas

Those chemical reactions in which gas is evolved such as

·       Zn + H2SO4 ZnSO4 + H2

·       C + O2 CO2

·       FeSO4 Fe2O3 + SO2 + SO3

2.     Formation of precipitate

Those chemical reactions which are characterized by formation of ppt such as:

·       BaCl2 + H2SO4 BaSO4 + HCl

·       CaOH2 + CO2 CaCO3 + H2O

·       Pb(NO3)2 + KI PbI2 + KNO3

·       AgNO3 + NaCl AgCl + NaNO3

3.     Change in colour

Those chemical reactions which are characterized by the change in colour such as:

·       FeSo4 Fe2O3 + SO2 + SO3

·       Pb(NO3)2 Pb0 + NO2 + O2

·       Citric Acid + KMnO4 Colourless

4.     Change in temperature

Those chemical reactions which are characterized by a change in temperature such as:

·       CaO + H2O Ca(OH)2

·       C + O2 CO2

·       CaCO3 CaO + CO2

·       Pb(NO3)2 PbO + NO2 + O2

5.     Change in state

Those chemical reactions which are characterized by a change in state such as:

·       C + O2 CO2

·       ZnS + H2SO4 ZnSO4 + H2

·       Ca(OH)2 + CO2 CaCO3 + H2O

·       CO + H2 CH3OH

Types of chemical reaction on the basis of heat

A.    Endothermic reaction

Those chemical reactions in which heat is absorbed to complete the reaction are called endothermic reaction.

·       CaCO3 CaO + CO2

·       Pb(NO3)2 PbO + NO2 + O2

·       FeSO4 Fe2O3 + SO2 + SO3

B.    Exothermic reaction

That chemical reaction in which heat is released along with the product is called exothermic reaction.

·       CaO + H2O Ca(OH)2

·       C +O2 CO2

·       Mg +O2 MgO

·       CH4 +O2 CO2 + H2O

NOTE: C6H12O6 + O2 CO2 + H2O + Energy (Respiration is also on endothermic reaction)