Formation Of Covalent Bond

                    Covalent bond occurs between the non-metal. Two atoms share their valence electrons. The two atoms sharing the outer most ( valence ) electron each other.

Formation Of Ionic Bond

                   Usually metals have low ionization energy, so that metals (Na) release some of their electrons to attain a stable configuration. Now the atoms becomes cations. Some of the non-metals (Cl) electron affinity is positive, so that non-metals accept the electron to attain a stable configuration. Anions are formed.

Example :

Na   +   Cl   →   Na⁺   +   Cl^-

Na⁺   +   Cl^-   →   NaCl

     A piece of sodium metal atom react with chlorine gas a vigorous reaction takes place, it will give sodium chloride a common table salt.

Key Point :

         Electron transfer from metal to non-metal atom.

                       Sodium atom transfer an electron to the chlorine atom the ions attract each other to form Na+ and Cl- ions. The lose of electrons from the sodium atom into a positively charged Na+ ions. ( cations ). The gain of electrons from the chlorine atom into a negatively charged Cl- ions. (Anions ). The cations and anions combine to form NaCl.

Types Of Solution

SOLUTE	SOLVENT	TYPE	EXAMPLE
Solid                                ( Zinc )	Solid                ( Copper )	Solid In Solid	Brass
Liquid             ( Mercury )	Solid                ( Silver )	Liquid In Solid	Dental Amalgam
Solid                ( Salt )	Liquid                ( Water )	Solid In Liquid	Seawater
Liquid                 ( Acetic Acid )	Liquid               ( Water )	Liquid In Liquid	Vinegar
Gas                 ( CO2 )	Liquid              ( Water )	Gas In Solid	Soda Water
Gas              ( Air )	Gas                 ( Nitrogen )	Gas In Gas	Air

Relationship Between Atomic Number, Mass Number and Istope

* For Example :   In Carbon-12 and Carbon-14,
¹²₆C                                                          ¹⁴₆C
Neutron - 6                                             Neutron - 8
Proton    - 6                                             Proton    - 6
Electron - 6                                              Electron - 6
Carbon-12 and carbon-14 have same atomic number and different mass number. It's known as isotopes.

* A number of proton in an atom is known as atomic number. Carbon-12 and carbon-14 both of them ontain 6 protons so that the atomic number is 6.
                 Z = 6
Z ==> Atomic number.

*    In carbon-12 , the mass number is 12 and the atomic number is 6. Mass number is bigger than the atomic number.Mass number is equal to the total number of protons and neutrons.

Saturated, Unsaturated, Super Saturated Solutions

  Saturated Solution :      
           A solution in which the maximum amount of solute has been dissolved. additional solute will not dissolve in a saturated solution. ( no more solute dissolve ).

Unsaturated Solution :
          A solution in which the lesser amount of solute is dissolved in it.

Super Saturated Solution :
          The solution that contains more of the dissolved materials ( solute ) at a given temperature than that of saturated solution is called super saturated solution. It is also known as super-cooling.

Solutions Types

       Based on the type of solvent solutions are classified into two types.

• Aqueous solution.
• Non-aqueous solution.

Aqueous Solution :

        The solution in which water is the solvent.

Example: Salt water ( salt in water would be represented as NaCl (aq).

Non-aqueous Solution :

          Non-aqueous means dissolved in something ( any liquid) other than water.

Example: Solution of sulfur in carbon disulphide.

Solubility

                    The amount of substance that will dissolve in a given amount of solvent is called solubility. Solubility is defined by two terms. Soluble and insoluble Or sparingly soluble.

Soluble:
  Soluble without limits is known as miscible. For example alcohol in water. Alcohol is soluble in water. So it will form a clear solution.

Insoluble :
   It is otherwise known as immiscible  or sparingly soluble. For example oil in water. Oil is insoluble in water. So the two liquids form a separate layer.

Solution

     A solution is a mixture of two or more substances. ( a solute and a solvent )
Solute     : The substances that dissolves. Present in minor amount.
Solvent   : Dissolving medium. Present in major amount.

Displayed Formula For Alkanes

Displayed Formula For Alkenes

Complete And Incomplete Combustion Of Alkanes

Complete Combustion:
    It gives carbon dioxide and water.

    CH₄      +     2O₂     →     CO₂     +     2H₂O

Incomplete Combustion:
    It gives carbon or carbon monoxide.

     CH₄     +     H₂O     →     CO     +     3H₂

Deffine Element

      An element is a substance consisting of atoms which all have the same number of protons. A chemical element is a substance that cannot be broken down by chemical means.
Eg: Copper, Cesium, Iron, Neon.

Periodic Trends Of Alkali Metals

• Ionization Energy:

Alkali metals have low ionization energy.
                     The first ionization energies of alkali metals are relatively low and decreases on moving down the group.

Reason:
   Atomic radius gets increases on moving down the group. so the outermost electron gets farther away from the nucleus and therefore the first ionization energy decreases.
   The second ionization energy of the alkali metals are high. The second most loosely held electrons is part of a fully filled electron shell and is thus difficult to remove.

• Electropositive Character:

Electropositive character increases go down the group.

                    M      →     M⁺      +     1e^-

Reason:
     The first ionization energy of alkali metals decreases down the group, it is easier to remove the outermost electron from the atom and the participate in chemical reaction thus increasing the electropositivity down the group. The alkali metals are high electropositive that they emit electrons when irradiated with light.This effect is known as photoelectric effect. Due to this property Cs and K are used in photoelectric cells.

• Melting And Boiling Point:

Alkali metals have low melting and boiling point.

Reason:

     The weak interatomic bonds are attributed to their large atomic radii and the presence of one valance electron. The atoms increases in size going down the group. The nuclei of the ions are move further away from the delocalised electrons and hence the metallic bond becomes weaker. Therefore the melting and boiling point decreases going down the group.

• Density:

Alkali metals have high density.

Reason:

     The trends for the densities of the alkali metals depends on their atomic weight and atomic radii. The densities of the alkali metals increases moving down the group with an exception at potassium. Lithium has low density due to the low atomic weight of the atom.

• Oxidation And Reduction:

Oxidation:

     Alkali metals have only one electron in their outermost valence shell. So they easily lose one electron in their outermost shell and form a stable configuration of the nearest inert gas. They are monovalent elements showing an oxidation state of +1.

Reduction:

     Alkali metals have low ionization energy, they easily lose their valence electron. Therefore these elements behaves as good reducing agents

• Atomic And Ionic Radii

            Atomic and Ionic radii of alkali metals are increases on moving down the group. The ionic radii of the alkali metals are much smaller than their atomic radii.

Uses of Hydrogen Peroxide

• Hydrogen peroxide is a bleaching agent delicate materials like silk, wool, hair which wool be destroyed by chlorine, are bleached with hydrogen peroxide.
• It act as a aerating agent in production of sponge rubber.
• It destroys bacteria and hence it is used as an antiseptic and germicide for washing wounds, teeth and ears.
• It is used as a oxidizing agent.
• It is used as an Antichlor.
• It is also used as a propellant in rockets.
• For pollution control of domestic effluents where it restores the aerobic conditions of sewage waste for pollution control of industrial effluents containing CN^-  ions. H₂O₂  oxidizes CN^- ions to harmless product. 

Chemical Properties Of Hydrogen Peroxide

Decomposition:
           Pure hydrogen peroxide is unstable and decomposes on standing. On heating water and oxygen are formed.

                             2H₂O₂     →     2H₂O     +     O₂ 

_{Oxidizing Nature} 

        It is a powerful oxidizing agent. It functions as an electron acceptor.

                              H₂O₂     +     2H⁺     +     2e^-     →     2H₂O

                                                                                  (In acidic solution)

                                               H₂O₂^-     +     2e^-     →     2OH^-

                                                                                   (In alkaline solution)

                                              2KI     +     H₂O₂      →     2KOH     +     I₂

                                                                                     (In neutral medium)

It oxidizes ferrous salts into ferric salts.

                           2Fe²⁺     +     2H⁺     +     H₂O₂     →     2Fe³⁺     +     2H₂O

Reducing Agent :

                        Ag₂O     +     H₂O₂     →     2Ag     +     H₂O     +     O₂

              Hydrogen peroxide act as a reducing agent. In above equation moist silver oxide is reduced to silver.

Addition Reaction:

Francium ( Alkali Metal )

• Francium was discovered by Marguerite Perey in 1939.
• Least electronegative element.
• It occurs as a result of an alpha disintegration of actinium.
• It can be produced by artificially bombarding thorium with protons.
• Francium is a heavy, unstable, radioactive metal with a maximum half-life of only 22 minutes.
• Highly radioactive.

Symbol                                 -  Fr
Atomic number                    -   87
Number of electrons            - 2, 8, 18, 32, 18, 8, 1
Electronic configuration    -  [ Rn ]7s¹

Melting point                       -  300 K
Boiling point                       -  950 K
Atomic weight                     - [ 223 ]

Atomic Structure:

Uses:

It is used for research purposes only. ( Due to its rarity and instability ).

Cesium ( Alkali metal )

• Cesium was discovered by Robert Bunsen and Gustar Kirchoff in 1860. From Latin word caesius (mean- Sky blue).
• Cesium metal is extremely reactive.
• Cesium is the least electronegative element with a stable isotopes.
• Cesium is found in the minerals pollucite and lepidolite.
• Cesium form alloy with other alkali metals and amalgam with gold.

Symbol                                -  Cs
Atomic number                  -  55
Number of electrons          - 2, 8, 18, 18, 8, 1
Electronic configuration  - [ Xenon ] 6s¹

Melting point                     -  301.5 K
Boiling point                     - 944 K
Atomic weight                   -  132.905

Atomic Structure:

Uses:

• Cesium is used in photoelectric cells, vaccum tubes and IR lams.
• Cesium is used in atomic clocks.
• Cesium hydroxide is used in etch silicon.
• It is used as a catalyst in the hydrogenation of few organic compounds.
• Cesium vapour is used in many common magnetometers.
• It is also used in chemical and medical uses.
• Cs-137 is a radioisotope used as a gamma emitter in industrial application.
• Cs-137 is also used in hydrologic studies.
• Cesium nitrate is used as an oxidizer and pyrotechnic colorants, to burn silicon in infrared flares.

Rubidium ( Alkali metal )

• Rubidium was discovered by Robert Bunsen in 1861. From Latin word Rubidus ( mean, Dark red or bright red) 
• Elemental rubidium is highly reactive and rapid oxidation in air.
• Rubidium may be liquid at room temperature.
• Rubidium compounds have various chemical and electronic aplications.
• Rubidium from amalgam with mercury and alloy with gold, sodium, potassium and cesium. 
• It is the 23rd most abundant element in the earth crust.
• It is the second most electropositive element.
• Occurs naturally minerals like leucite, pollucite, carnalite and zinnwaldite.

Symbol                                 -  Rb

Atomic number                    -  37

Number of electrons           - 2, 8, 18, 8, 1

Electronic configuration   -  [ Krypton ]5s¹

Melting point                      - 312.46 K

Boiling point                      - 961 K

Atomic weight                     - 85.46

Atomic Structure :

Uses:

• Rubidium chloride is used in biochemistry.
• Rubidium-87 is used in some atomic clocks to maintain accuracy.
• Rb is used as a 'getter' in vaccum tubes and making special glasses.
• It is easily ionised and so has possible use in 'ion engine' for space vehicles.

Potassium ( Alkali Metal )

•  Potassium was discovered by Humphry Davy in 1807. 
• It is derived from caustic potash ( KOH potassium hydroxide ). In Latin Kalium.
• The metal must be stored in mineral oil, such as kerosene as it oxidizes rapidly in air and catches fire spontaneously when exposed to water.
• Potassium ions are necessary for the function of all living cells.
• Soft silvery white alkali metal and very reactive in water.
• Sylvite, langbernite, carnalite and polyhalite from extensive deposits in ancient lake and sea beds from which potassium can be obtained.

Symbol                                 - K

Atomic number                    -  19

Number of electrons           -  2, 8, 8, 1

Electronic configuration   - [ Argon ] 4s¹

Melting point                      - 336.53 K 

Boiling point                      -  1032 K

Atomic weight                     - 39.098

Atomic Structure:

Uses: 

• Potassium is a mineral that plays many critical roles in the body.
• Potassium is used for treating and preventing low potassium levels.
• Potassium is in high demand as a fertilizer.
• Metallic potassium is used in several types of magnetometers.
• Potassium also used in food preservative, bleach textile and straw and in tanning of leathers.
• Potassium salts have many commercial uses.

Sodium ( Alkali Metal )

• Sodium was discovered by Humphry Davy in 1807. From the Latin name of sodanum (headache remedy)
• It is a bright silvery metal and highly reactive than lithium.
• Sodium floats on water, which decomposes it to evolve hydrogen and form the hydroxide.
• It is a soft metal readily cut with the knife and is a good conductor of electricity.
• Sodium is relatively abundant in the sun and other stars.
• Sodium occurs in many minerals such as Cryolite, Zeolite, amphipole and sodalite.
• It is not found free in nature.

Symbol                                -  Na

Atomic number                  - 11

Number of electrons          - 2, 8, 1

Electronic configuration  - [ Neon ]  3s¹

Melting point                     - 370.87 K

Boiling point                      - 1156 K

Atomic weight                    -  22.9897

Atomic Structure:

Uses:

• Sodium vapour is used in lamps for street light.
• It is used for manufacture of sodamide, sodium cyanide, sodium peroxide and sodium hydride.
• Sodium compounds are used in glass, paper, chemical, soap, petroleum and metal industries.
• It is used in the reduction of organic ester and preparation of organic compounds.
• The alloy of sodium and potassium is ( NaK )- It is a good chemical reducing agent and heat transfer agent.
• Sodium metal is used in the preparation of (tetraethyl lead) PbEt₄ and titanium metal from PbEt₄
• Sodium chloride is important for animal nutrition.