Tuesday, November 6, 2012

Bent Bond

                       Bent bonds are also known as banana bond. sterically hindered molecules whose binding orbitals are forced into a banana like form. Bent bonds are often more susceptible to reaction than ordinary bonds.

  Cyclopropane  ( C3H6 )

3c- 4e Bond

                               The 3 center 4 electron bond is a a model used to explain in hypervalent molecules such as phosphorus pentafluoride, sulfur hexafluoride ane xenon fluorides. It is also known as Pi mentel - Rundle three center model.

Quadruple Bond

                          A quqdruple bond is a type of chemical bond between two atoms involving 8 electrons. This bond is an existension of the more familiar types double bond and triple bond. Stable quatruple bonds are most common among the transition metal , in the middle of the d block such as tungsten and chromium. Typically the ligands that support quadruple bonds are pi donors . not in pi acceptors.
                         Valence bond theory predicts a quatruple bond as the only way to satisfy the octet rule for carbon in dicarbon. However MOT shows that three are two sets of paired electrons in the sigma system. (one bonding and one anti bonding)  and two sets of paired electrons in a degenerate pi bonding set of orbitals. This adds up to give a bond order of 2 , meaning that three exist a double bond between the 2 carbon in a C2 molecule. This is surprising because the MO diagram of diatomic carbon would show that three are 2 pi bonds and no sigma bonds.

Triple Bond

                    A covalent bond formed between three atoms by the mutual sharing of three electron pairs is called Triple bond. Triple bonds are denoted as three lines in chemical structure diagram. Triple bonds are stronger than single bonds or double bonds and they are also shorter. The bond order is three.



Double Bond

                        A covalent bond formed between two atoms by the mutual sharing of two electron pairs is called double bond.Double bonds are drawn as two parallel lines in chemical structure diagrams. Double bonds are shorter than single bond.The bond order is two.Double bonds are also electron rich , which makes them reactive.

           Ethylene (C2H4) is a hydrocarbon with a double bond between the two carbon atoms.


Friday, October 12, 2012

COVALENT BOND : ( chemical bonds )

               A bond between the two atoms are formed by the sharing of electrons. Which generally form between two non- metals. Example Nitrogen dioxide.

                Covalent compounds cannot dissociate into the water. So poor conductor of electricity in aqueous solution.


                   Covalent compound exist as a separate molecules. Because they are formed by neutral atoms and the force of attraction between these molecules is small.

                   Due to weak inter molecular forces generally covalent compounds are liquid and gases. Some covalent substances are solid like iodine.

                   They are volatile.

                   Generally they have low melting point and boiling point.

                    Covalent compounds are generally in soluble in water.

                    Covalent compounds are non - electrolyte because they do not conduct electricity.

  •  Non polar covalent compounds do not conduct electricity.
  • Polar covalent compounds conduct small amount of electricity. 


                          A bond between the two ions are formed from the transfer of one electron to another. Which is generally form between a metal and non-metal. For example NaCl. ( Sodium chloride ). This is often described as one atom giving electron to the other. In the case of NaCl , Sodium would give electron to chlorine.

                           Ionic compounds dissociate into their ions when they dissolve in water. It will react a good conductors of electricity in aqueous solution.


          Due to strong force of attraction, all ionic compounds are exist in solid state. At room temperature forming a crystal lattice structure.

            Ionic compounds have high melting point ( m.p) and boiling point (b.p )

             They are strong electrolytes. In solid state they do not conduct electricity. In molten state and in aqueous solution they conduct electricity.

             Generally ionic compounds are soluble in water and  insoluble in organic compounds.

              They are very hard.

REACTIVITY :         
               Ionic compounds are very reactive .

               Ionic compounds are low thermal conductivity.
  • Most of the ionic compounds are brittle and break under stress. Because ions produced by electron transfer attract each other by electrostatic attraction and this creates an ionic bond.


                A covalent bond formed by the mutual sharing of one electron pair between two atoms is called single bond. It is denoted by the single short line (-) In single bond formation each atom provide one electron. Usually single bond is sigma bond. But in diboron is pi bond .

Example :
      Single bond between the oxygen and each hydrogen in water molecule ( H2O ). Each of the covalent bond contains two electrons. One from hydrogen atom and one from oxygen atom. Both atoms share the electrons.


              In chemistry delta bonds are the covalent chemical bond formed between the overlap of 4 d orbitals between two atoms. The Greek letter delta ( ) in their name refers to d orbitals. Some ruthenium and molybdenum compounds contain a quadruple bond, consisting of one sigma bond , two pi bond  and one delta bond.


    In chemistry pi bonds are the covalent chemical bonds formed between the two neighboring atoms unbounded P orbitals.
    An unbounded P orbitals electron in one atom forms an electron pair with the neighboring atoms unbound parallel P orbital electron. This electron pairs forms the pi bond. Double bond and triple bonds are usually made up of  single sigma bond and one or two Pi bonds. Pi bonds are generally denoted by the Greek letter ( ) . Pi bonds are usually weaker than the sigma bonds.    


                In chemistry sigma bonds are strongest type of covalent chemical bond. They are formed by direct overlapping between two adjacent atoms in the outer most orbitals. i.e Sigma bonds are the strongest type of covalent bonds due to direct overlap of orbitals and the electrons. In these bonds are sometimes reffered to as sigma electrons.Sigma bonds are most clearly defined for diatomic molecules using the language and tools of symmetry groups. Common forms of sigma bonds are S+S, Pz+Pz, S+Pz, and dz2+dz2.

                     Z ==> Defined as the axis of  bond.
sigma symbol is denoted by the Greek letter . 

Friday, October 5, 2012

Metallic Bond

                                 The reaction between molecules within metals are called alkali reactive force. It involve the sharing of free electrons among a lattice of metal atom.


  • Metals are strength, malleability, ductility, luster ( shiny appearance ) conduction of heat and electricity.
  • An alloy is a solution of metal , often used to make a metal rope, metal plates etc.
  • The electrons and the positive ions in the metal have a strong attractive force between them. So the metals have the high melting point Or boiling point.The principle is similar to that of ionic bonds.  
           The strength of metallic bond depends on three things.
  1. The number of electrons that becomes delocalized from the metal.
  2. The charge of the cation.
  3. The size of the cation.
  • Metals that are malleable can be beaten into thin sheets. For example aluminium foil.
  • Metals that are ductile can be drawn into wires. For example copper wire.

Intramolecular ( Strong )

Chemical Bonds:
  1. Ionic Bond
  2. Covalent Bond
  3. Metalic Bond 
Types of covalent bonds :
  • Sigma bond.
  •  Pi bond.
  •  Delta bond
  • Gamma bond
  • Single bond 
  • Double bond 
  • Triple bond
  • Quadruple bond 
  • Quintuple bond
  • Sextuple bond
  •  3c-4e  .   4c - 2e
  • Agostic bond 
  • Bent bond
  • Dipolar bond
  • Pi back bond
  • Hapticity
  • Antibonding
  • Conjugation 
  • Hyper conjugation
  • Aromaticity
  • Metal aromaticity.
                            The force of attraction that exist between bonds within a molecule. They contain all types of chemical bond. They are stronger than inter-molecular forces.

TYPES OF INTRA MOLECULAR FORCES :                       

                            There are three main types of intramolecular forces distinguished by the types of atom and the behaviour of electrons.
  • Ionic bond
  • covalent bond
  • Metalic bond

Thursday, September 13, 2012

Blue Bottle Magic Tricks


  • Tap water
  • 2 one litter conical flask with stopper.
  • 7.5 g glucose         ( 2.5 g for one flask : 5 g for other flask )
  • 7.5 g NaOH          
  • 0.1 % solution of methylene blue  ( 1 ml for each flask )
  • Half fill two one liter conical flasks with tap water.
  • Dissolve 2.5 g of glucose in one of the flask ( A ) and 5 g of glucose in the other flask ( B )
  • Dissolve 2.5 g of NaOH in flask A and 5 g of NaOH in flask B.
  • Add 1 ml of 0.1 % of methylene blue to each flask.
  • Set a flask a side. The liquid will gradually becomes colorless.
  • The blue color of the solution can be restored by shaking the contents of the flask.
         Gluconic acid is converted to sodium gluconate in the presence of NaOH. Methylene blue speeds up this reaction by acting as an oxygen transfer agent. By oxidizing glucose, methylene blue is itself reduced ( leucomethylene blue ) and becomes colorless. Leucomethylene blue is re-oxidized and the blue color of solution can be restored.

Super Cooling Water


  • 20 ml of distilled water
  • Bowl
  • Glass 
  • Ice cubes
  • Salt
  • Pour 20 ml of distilled water into a very clean glass.
  • place the glass in a bowl of ice cubes such that the level of ice is higher than the level of water in the glass.
  • Sprinkle 2 tsp of salt on the ice.
  • Allow about 15 minutes for the water to cool below freezing.
  • Insert the thermometer into the glass of water. When the temperature of the water below freezing, the water has been super cooled.
  • Make the water freeze by pouring it over a piece of ice.
          Chill water below its freezing point without having it turn into ice. Then pour the water or shake and watch it crystallize before your eyes.

Pepper And Water Tricks


  • Pepper 
  • Water
  • Dish washing liquid
  • Plate Or Bowl
  • Pour water into a plate.
  • shake some pepper into the water.
  • Dip the finger into the plate. Nothing much happens.
  • Put a drop of dish washing liquid on finger and dip it into the plate the pepper will rush to the outer edges of the plate.
           Add detergent to water the surface tension of water is lowered. So the water wants to spread out. So the water is carried the pepper to the outer edge of the plate.

Wednesday, September 12, 2012

Change Water Into Blood


  • Sodium carbonate
  • 2 glass
  • Phenolphthalein indicator
  • Rod 

  • Ferric salt
  • Ammonium thio cynate OR Pottasium thio cynate .
  • Coat sodium carbonate to the bottom of a glass.
  • Fill the second glass half full of water. Add 10 drops of phenolphthalein indicator solution to the glass.
  • To change water into blood , pour the water into the glass containing the sodium carbonate.
  • Stir well the water will change from clear to red.

Burning Money

               A combustion reaction occurs between alcohol and oxygen producing heat, light, carbon dioxide and water. Rupee not is soaked an alcohol water solution, the alcohol has a high vapour pressure and is mainly on the out side of the material. when the rupee is lit the alcohol is what actually burn ? The temperature at which the alcohol burns is not high enough to evaporate the water which has a high specific heat so the rupee remains wet and isn't able to catch fire on its won.

                   After alcohol burned, the flame goes out.


  • Mix 50 ml of water with 50 ml 100% pure alcohol.
  • Add a pinch of salt to the solution
  • Soak a rupee into the solution, that it is thoroughly wet.
  • Use tongs to pick up the rupee.
  • Allow any excess liquid to drain it.
  • Move the rupee away from the solution.
  • Light the rupee on fire and allow it to burn until the flame goes out.
  • Alcohol has high vapour pressure. So alcohol easily catch fire and burns quickly.
  • But the temperature not enough to the water. so the rupee remains wet. Isn't able to catch the fire.

Egg in a Bottle


  • Egg ( boiled one )
  • Conical flask
  • Paper
  • Match box
  • Take a piece of paper, fire it and drop it into the bottle.
  • Set the egg on the top of the bottle.
  • When the flame go out , the egg will get pushed into the bottle.

  • Pressure of the air present in inside and out side of the bottle same.
  • Change the temperature of the air inside the bottle that time the pressure also change inside the bottle.
  • So that inside the pressure decrease and the out side pressure increase .
  • So high pressure will push the egg into the flak.

Baking soda volcano


  • 4 cups flour
  • 2 tsp salt
  • 3 tsp cooking oil
  • Warm water
  • Plastic soda bottle
  • washing detergent 
  • Food coloring
  • Vinegar
  • Baking dish
  • baking soda
  • Mix 4 cup of flour, 2 tsp of salt, 3 tsp of cooking oil and warm water.  Make them dough.
  • stand the soda bottle in the baking pan and mold the dough around into a cone shape. Don't cover the hole.
  • Fill the bottle with warm water and a pinch of orange food color.
  • Add detergent to the bottle.
  • Add 2 tsp of baking soda to the liquid.
  • Slowly pour vinegar into the bottle.
  • Watch out- eruption time.

       The chemical reaction between the baking soda and vinegar. in this reaction carbon dioxide gas is evolved. The same reaction present in real volcanoes also. 

Bend water


  •  Nylon comb or Latec balloon .
  • Water faucet.
  • Dry the hair with nylon comb.
  • Turn the tap water a narrow stream of water is flowing.
  • Move the comb close to the water. Now the narrow stream of water bend towards the comb.
  • The amount of bend depends on how close the comb is to the water 

Monday, June 18, 2012

Why Smoking Causes Cancer ?

                                          Tobacco smoke contain more than 60 carcinogenic compounds. 4000 individual substances identified in tobacco smoke, including carbon monoxide, hydrogen cyanide, ammonia and other toxic irritants. The main reason is tobacco contains nicotine. Nicotine is a additive content which alters brain functioning.

                                           Nicotine is naturally occurring liquid alkaloids. When a man smoke nicotine is absorbed through the skin and mucosal lining of the mouth and nose and by inhalation int he lungs. In the body it activate the same reward system as do other drugs such as cocaine. in the brain nicotine increases the level of neurotransmitter dopamine. so the brain responsible for feeling pleasure. People continue dosing themselves frequently throughout the day to maintain the pleasurable effects of nicotine and to prevent withdrawal symptoms.

Why do onion make you cry ?

                                   Onion cells contain some chemical compounds like sulfur. Cut the onion its cells are broken and the chemical compounds are released into the air. So that more volatile sulfured products are formed. Sulfured compounds react with the moisture in eyes forming sulfuric acid. Which produce a burning sensation. So that the tears comes out.

How To Avoid ?

  • Chop the onion under cold water. The volatile sulfured compounds will be released but then they react  with the water, instead of reaching your eyes.
  • You can freeze the onion for 10 minutes before cutting it. The cold temperature of the onion will slow down the chemical reaction which forms the volatile sulfured compounds.

How meals are cooked faster in a pressure cooker ?

                                         A pressure cooker is like a pot but with a more elaborated lid that seals the pot completely. Heat water inside the pot, it boils and the steam cannot escape.So it remains inside and the pressure is increases. Under pressure cooking temperature raise much higher than under normal condition. So the food is cooked much faster.

How Soap Clean ?

                           Substance which can be dissolved in water and others that cannot. For example water and oil. water and oil do not mix together. So we try to clean oil stain from a cloth or hand water is not enough. So we need a soap.
                           Soap is formed by a molecules of hydrophilic and hydrophobic. So that soap molecules act like a diplomat, and improving the relation ship between water and oil.

                    When soap is added to the water

  • The hydrophilic heads of molecules stay into the water.
  • The long hydrophobic chain join the oil.
                      Then they formed circular groups named micelles, with the oil material absorbed inside and trapped. An emulsion of oil in water is then formed after that the oil particles becomes suspended and dispersed into the water. Soap cleans by acting as an emulsifier. It allows oil and water to mix. So that oily grime can be removed during rinsing.

Tuesday, June 5, 2012

Thrust :

                  All aero planes with engines and all rockets depend on thrust. Thrust makes them move forward. They push large amount of air or other gases in one direction. This makes the aircraft fly in the other direction. Now you can see how thrust work in these experiments with balloons.

Things need :

o   Long balloon
o   Heavy paper
o   Tape
o   Felt-tipped pens

Uncontrolled flight :

   v  Use felt-tipped pen to decorate the balloon as an aero plane if you like. It is easier to draw on the   balloon if you blow it up first. Do not tie it shut. Tie it round a matchstick or a pencil.
   v  Cut wings from the heavy paper. Tape them to the Centre top of the plane.
   v  Remove the matchstick or pencil. Blow the balloon up as full as you can. Let it go. Thrust will make it fly around the room in a series of loops and turns until it runs out of air. 

Make the lemon peel dive :

Things need :

    §  Piece of balloon
    §  Lemon peel
    §  Broad mouthed bottle or rubber band
    §  Water

Instruction :

v  Fill the bottle with water till the brim.
v  Put a peel or lemon in the shape of a boat in water.
v  Stretch the piece of balloon on the mouth of the bottle and with the rubber band seal it in place on the mouth of the jar. The balloon should be slightly stretched. It should not sag.
v  Using you finger gently press down on the lid (balloon cover ) and the lemon peel will dive to the bottom of the jar.
v  Release you finger the lemon peel will return to the top of the jar.
Why ?
              The pressure exerted by hand squashes air bubbles in the lemon peel allowing the water. This makes the lemon peel heavy and sink. When the finger is released the air in the lemon peel expands and returns to the top.

Bring the balls together :

Things need :

   §  Ping pong balls
   §  Table
   §  Straw
Instruction :

            ·         Place the ping pong balls a short distance a part on a table.
            ·         Use the straw to blow air between them. The ball move towards each other.

Why ?
                   Air presses on all things. This is called air pressure. When you blow between the ping pong balls, you blow away the air that is between them. This means that air is no longer presses against one side of each ball. But air still presses against the other sides of the balls, and that air pressure pushes the ball together.

Make the paper rise :

Things need :

v  A piece of paper

Instruction :

  •    Hold a piece of paper by the corners of edge.
  •    Bring it up to your mouth. The paper will droop towards the floor.
  •    Blow gently across the top surface of the paper. Does the paper still droop.
  •    Take a deep breath and blow harder.
  •    The paper rise. Before you blow, the air on both the sides of the paper is still.

§                                                    The pressure is same on both the sides. When you blow over the upper surface, the pressure on the side is reduced. But the pressure underneath is the same as before. The higher pressure underneath forces the paper up. Blowing harder reduces the pressure on the upper surface even more.  This makes the paper rise even higher.

Why water won’t run through the bottle ?

Things need :

            ·         Glass jar with narrow neck
            ·         Funnel
            ·          plasticine
            ·         Screwer
            ·         Water

Instruction :

           *      Position a funnel in the neck of the jar.
           *      Seal it tightly with plasticine.
           *      Fill the funnel with water.

The water cannot flow into the jar. Now  make a hole in the plasticine , the water flow into the jar because the pressure is same inside and outside of the jar.

( i.e ) why you need to make a holes before you can pour liquid from a tin.

Make your own fossil :

Things needed :

             ·         Plasticine
             ·         2 paper cups
             ·         Plaster of paris
             ·         Water
             ·         An object that you would like to use as the fossilized impression

Instructions :

   v  Flatten a ball of plasticine until it is about 2 cm thick while making sure the top is smooth.
   v  Put the plasticine inside the paper cup with the smooth side facing up. Carefully press the object you want to fossilize into the plasticine until it is partially buried.
   v  Carefully remove the object from the plasticine. An impression of the object should be left behind.
   v  Pour half cup of plaster of paris and stir until the mixture is smooth.
   v  Leave it for around 2 minutes.
   v  When the mixture has thickened, pour it on top of the plasticine in the other cup. Leave the mixture until    the plaster has dried.
   v  When the plaster has fully dried, tear away the sides of the paper cup and take out the plasticine and plaster. Keep it in a warm dry place .

Effect of acid rain on rocks :

Things required :
  •   Plastic cup
  •  Vinegar
  •   Water
  •  Small piece of lime stone

How it’s react ?
 o   Take a plastic cup. Take half cup of vinegar. ( vinegar is an acid )
 o   Place a small piece of lime stone in the cup of vinegar.
 o   Allow it to soak for several days.
 o   Remove the lime stone and observe carefully.

Why ?
                 In nature when rain water combines with carbon dioxide in air or with carbon dioxide from decaying organic matter , carbonic acid is produced. When the acid flows through cracks in limestone, it chemically reacts with the rock forming dissolved calcium, which is carried away in water.



Effect of frost in rocks :

Things needed :
           *      Two paper cups
           *      Freezer
           *      Plaster of paris
           *      Water
           *      Scissors
           *      Butter knife

Ø  Take a cup of about 3 inches height.
Ø  Prepare plaster of paris in the cup.
Ø  Use the butter knife to cut a narrow one inch deep groove into the plaster of paris before it dries.
Ø  The grooves should not touch the edges of the container.
Ø  Allow it to dry completely.
Ø  Carefully tear the container away to reveal your block. Measure the size of the groove. Fill the groove with water and place the block in the freezer.
Ø  After the water has frozen, remove the block and record your observation. Allow the ice to melt and place it in the freezer again. Repeat this till the block brakes.

Make a sand stone :

Things needed :
v  Fine sand
v  Two paper cups
v  Water
v  Epsom salt
How to make ?
   v  Take a paper cup. Drop 1 inch of fine salt into it.
   v  Fill another cup with water  about 1 inch high.
   v  Add Epsom salt slowly with stirring still no more salt dissolves.
   v  Pour the Epsom salt solution over the sand in the cup. Stir well.
   v  Place the mixture in a place where it will dry.
   v  It will take few days to dry.
   v  When it is completely dry, take the paper cup away from the sand.

Thursday, May 31, 2012

Sun loving algae

You will need :
A jar with a lid and some pond water, aluminum foil.
  • ·         Fill the jar with the pond water , and cover it with a lid.
  • ·          Wrap the jar up completely with aluminum foil. Make sure that there are no uncovered places.
  • ·         Now cut a small hole, about 1 centimeter wide, in the foil.
  • ·         Place the jar on a window sill. Turn the hole towards the light. Leave it there for few hours.
  • ·         Carefully remove the foil without disturbing the water.
  • ·         You will find that the algae has clustered around the spot where the light entered through the hole.

Wednesday, March 14, 2012

Water to Ink to Lemanite to alcohol


  • Take a beaker add tannic acid and 3 drops of ferric alum.It will be converted into ink.
  • To the ink add citric acid. It will be converted into lemanite.
  • To the lemanite add dilute ammonia. It will be converted into alcohol.
  • To the alcohol add dilute sulphuric acid . It will be converted into water. 

Naphthalene Balls Dancing


  • 500 ml beaker
  • 400 ml water
  • Sodium bicarbonate
  • Citric acid
  • Naphthalene ball
  • Take a 500 ml beaker add sodium bicarbonate ,citric acid and 400 ml of water. Cover the beaker with lid.
  • Put naphthalene balls into the solution. The balls go up and down. It's look like a dance.
WHY ? 
            Sodium bicarbonate react with citric acid to evaporate carbon dioxide gas. So that the naphthalene balls going up and down.