Saturday, October 11, 2014

Radioisotope

             A radioactive isotopes are called radioisotopes. It will produce the radio active naturally or artificially. ( some chemical elements have the unstable nucleus so it will decay to give a stable nucleus.The element decay time some radio activity will produce. This type of isotopes are called radioisotopes.

Atomic Mass

                The mass of an atom of a chemical element weighed by how abundance each isotopes in nature. It is also known as average atomic mass Or atomic weight.

Isotope

           Atoms of an element with the same atomic number and different mass numbers are called isotopes.
Example :
Protium Or Hydrogen . (1H1)      
 Deutrium Or Heavy water. (1H2)
Tritium.    (1H3)

Mass Number

               The total number of protons and neutrons in an atom is known as mass number. It is represented as the letter ' A '. It is also known as nucleon number.

Example :

                    199F       21H
* The bigger number 19 is mass number.
* The smaller number 9 is Atomic number.

Atomic Number

              The number of protons in an atom is known as atomic number. ( which means number of protons equal to number of electrons). It is otherwise known as proton number.It id represented as the letter ' Z ' .
Example:
Atomic number of oxygen,  Z = 8
Atomic number of hydrogen, Z = 1
Atomic number of carbon, Z = 6

Wednesday, October 8, 2014

Hetero-nuclear Diatomic Molecule

                   Diatomic molecules are chemical compounds of two different elements combine to form hetero-nuclear diatomic molecules. It depends on the temperature and pressure.
Example: Carbon monoxide, Hydrogen-fluoride, 

Homo-nuclear Diatomic Molecule

           Chemical compounds of two same elements combine to form a stable homo-nuclear diatomic molecule at standard temperature and pressure.
Example: Hydrogen, Nitrogen, Oxygen.

Diatomic Molecule

                   A molecule which contains two atoms of the same elements or different elements is called diatomic molecule. 'Di' means "Two". Noble gases do not form the diatomic molecule.
Example: Hydrogen, Nitrogen, Oxygen, Carbon monoxide.

Monatomic Molecule

          A molecule which contains only one atom is called monatomic. "Mon" means 'one'.
Example: Noble gases.

Atomicity

            The total number of atoms present in one molecule of an element is called atomicity.

Combined Gas Law

         It is a combinations of three laws. Boyle's Law, Charles' Law, Gay-Lussac's Law. The ratio of the product of pressure and volume and the temperature of a system remains constant.
Written by mathematically,
PV/T  = k
P  --> pressure
V --> volume
T --> temperature
k --> constant

Charles' Law

               At constant pressure the volume of a gas is directly proportional to the temperature.The law was stated by the scientist Jacques Charles.
Written by mathematically,
V/T = k
V  --> volume of the gas
T  --> temperature of the gas (kelvin)
k  --> constant

Boyle's Law

                    At constant temperature the volume of ideal gas is inversely proportional to its pressure. The law was named after scientist Robert Boyle.
Written by mathematically,
    PV = k
P  --> pressure of the gas
V  --> volume of the gas
k   --> constant 

Avogadro's Law

                Equal volume of same gases, at the same temperature and pressure, contains the equal number of molecules. It is otherwise known as Avogadro's principle. This law was stated by the Italian chemist Ameden Avogadro.
Written by mathematically,
        V/n =  k  
V --> volume of the gas
n  --> amount of substance of the gas (moles)
k  --> proportionality constant

Tuesday, October 7, 2014

Homogeneous Mixture

                  Homogeneous refers to the state in which two or more substances, that are uniformly distributed throughout the mixture.
Example: Air, Blood, Sugar water, Salt water. 

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.

Unsaturated Solution

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

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 ).

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.

Endothermic

                 The term endothermic describes a process which absorb energy in the form of heat. Endo means " within "
Example : Melting ice cubes.

Exothermic

                 The term exothermic describes a process or reaction that releases energy in the form of heat. some times in the form of light, electricity or sound. Exo means " outside "
Example : Rusting iron.

Helmholtz Free Energy

                       Amount of energy either absorbed or released in a closed system at constant temperature and volume. It is denoted as A. A is defined as,
                                   A  =  U - TS
A  -->  Helmholtz free energy
U  -->  Internal energy
T  -->  Temperature
S  -->  Entropy

Gibbs Free Energy

                      It is a thermodynamic property. It was defined by Josiah Willard Gibbs. It is denoted as G. Gibbs free energy is the energy associated with a chemical reaction that can be used to do work. The process will occur spontaneously at constant temperature and pressure. G is defined as,
                                 G  =  H - TS
H  -->  Enthalpy
T  -->  Temperature ( Kelvin )
S  -->  Entropy

Free Energy

               The internal energy of thermodynamic system that can be converted to do work.

Entropy

                      Entropy is commonly known as a measure of the disorder or randomness of a system. It is denoted as S.

Enthalpy

              Enthalpy is a thermodynamic property of a system. It is denoted as H. Amount of energy in a system capable of doing mechanical work is known as enthalpy. ( Enthalpy is the amount of heat content used or released in a system at constant pressure ).

Acid

                    Acid is an entity that can transfer (donates) a proton or accept electrons. Sour taste. Turn blue litmus to red.

Base

              A base is an entity that can donates electrons or that accepts proton. Bitter taste. Turn red litmus to blue. 

Ideal Gas Law

                PV =  RT
P  -->  Pressure
V  -->  Volume
R  -->  Ideal gas constant
T  -->  Absolute temperature

Monday, October 6, 2014

Vander Waals Forces

                 Attractive forces between uncharged molecules are known as vander-waals forces.             ( vanderwaals forces include attractions between atom, molecule and surface as well as other inter molecular forces ).
           
                                 (P  +  a/V2)    V  -  b   =  RT
P  ==> Pressure
a  ==> Attraction between individual gas particle.
V ==> Volume
b  ==> Average volume of individual gas particles.
R ==> Ideal gas constant.
T ==> absolute temperature.

Sodium Carbonate


  •  Sodium carbonate molecular formula is Na2CO3.
  •  Pure sodium carbonate is white in color and odorless powder.
  • It is otherwise known as washing soda, soda ash, alkali soda and soda crystals.

Resonance Energy

              The difference in energy between the dicentric and the polycentric states is called resonance energy of the molecule.

Double bond

                  Two atoms may share two electrons with each other to give a double bond.

Trible bond

                Three atoms may share three electrons with each other to give a trible bond.

Diagonal Hybridization

                  Hybridization of s orbital and p orbital is called diagonal hybridization.

Trigonal Hybridization

                   Hybridization of three atomic orbitals are called trigonal hybridization.

Nodal plane

               A plane in which the probability of finding the electron is zero.

Covalent Bond

              Sharing of electrons is known as covalent bond. Otherwise known as covalence or Electron-pair bond.

Ionic Bond ( Electrovalence )

              The attractive force between ions of opposite charge is called ionic bond or electrovalence.   ( Atom loses an electron to form a positive ion other atom gain an electron to form a negative ion )

Ions

                Charged particles are called ions. Due to loss or gain of one or more electrons.

Electron Affinity

               The energy released when an isolated atom requires an additional electron.

Electronegative

                   Atom has gained an electron and become negatively ( - ve ) charged that is called electronegative elements.

Electropositive

                  Atom has lost an electron and become positively charged that is called electropositive elements.

Ionization Potential

               The energy necessary to remove an electron from an atom or molecule.

Parallel Spins

                   Electrons with parallel spins are represented by arrows pointing in same direction.

Opposite Spin

                  Electrons with opposed spins are represented by arrows pointing in opposite directions. 

Hund Rule

                Two electrons usually do not occupy a given orbital in a sub-shell until all of the orbitals of the sub-shell have at-least one electron.

Pauli Exclusion Principle

              No orbital can contain more than two electrons and these electrons must have opposite spin.

Orbital

        Orbital is the mathematical expression describing the behavior of an electron moving in the vicinity of a positively charged nucleus.

M - Shell

        A third shell with a maximum of eighteen electrons.

L - Shell

        Second shell with a maximum of eight electrons.

K - Shell

     First shell with a maximum of two electrons.