- Elements with each electrons in their valence shell ( state of octet) are said to be most stable form of electronic configuration and such elements do not take part in bond formation.
- Inert gas elements (except , which is duplet) passes such stable electronic configuration.
- Element attain octet state either by the transfer, sharing or coordinate of valence electrons.
Electro valency (Electrovalent/Ionic bond):
- Formation of bond is exothermic process (i.e. energy releases).
- The bond formation by the complete transfer of electron from valence shell is called electrovalent bond.
- Electro valency is the number of electrons gained or lost.
Characteristics of Ionic Bond:
- They generally have high melting and boiling point.
- They are highly soluble in solvents with high dielectric constant but insoluble in non-polar solvent like benzene, ether, etc. The ions dissolve in water if .
- They do not conduct electricity in solid state but conducts electricity in molten or solution state.
- Favourable condition for formation of ionic bonds are low charge in ions, large cation and small anion.
-No bond is ionic, it has same of covalent character which is given on the basis of Fajan's rule:
a) Size of cation:
-Smaller is the cation, greater is its polarizing power.
-Thus, with smaller ion is more covalent than .
b) Size of Anion:
-Bigger the anion, larger is its polarizing ability.
-The covalent character of Lithium halides is:
c) Charge of the ion:
-Covalent character increases with increase in charge.
-Covalent Characters is in order:
d) Electronic Configuration:
-When two cation have same charge and size, the one having electrons in outermost shell will have larger polarizing power than a caution having electrons in outermost shell.
- is more covalent than
e) If the electronegativity difference between combining molecules then the bond formed will be ionic.
Covalency (Covalent Bond):
- Bond formed by the mutual sharing of valence electrons.
- If difference of electronegativity , , the bond will be polar-covalent.
- If difference of electronegativity , , the bond will be non-polar covalent.
- E.g. .
Characteristics of Covalent Bond:
- These compound are molecular in nature.
- They are insoluble in water and soluble in non-polar solvents like benzene.
- It is a weaker bond. So, they have low melting and boiling point.
- Unlike ionic compound, covalent compound can show structural and space isomerism.
Co-ordinate Covalent or Dative Bond:
- Special type of covalent bond, which is formed by one sided sharing of lone pair of electrons.
- The atom that donates a pair of electron is called donor and atom which accepts the electron pair is called acceptor.
- It is represented by .
Characteristics of Co-ordinate Covalent Bond:
- They exists in all three states .i.e. solid, liquid and gas.
- They show isomerism and stero-isomerism.
- They are poor conductor of electricity.
- Their melting points and boiling points are greater than covalent compounds and less than ionic compounds. E.g. .
- has both ionic and covalent bond.
- has covalent and co-ordinate bond.
- contains all three types of bond. i.e. Ionic, Covalent and Co-ordinate covalent bond.
- has ionic, covalent, coordinate and hydrogen bond also.
- Mixing of two or more than two atomic orbitals.
-Shape: Linear geometry.
-Shape: Triangular geometry
-Shape: Pentagonal bypyramidal
- The hybridization can also predicted by formation of and bond.
- -bond is strong bond. During formation of atom, lone pair is converted as bond.
-If no. of bond=, hybridized.
If no. of bond=, hybridized.
If no. of bond=, hybridized.
-In Aniline and Phenol, N and O atom is -hybridized since lone pair of electron is involved in resonance.
-Structure of molecule is linear.
-Hybridization of in benzene is hybridized.
-In Diamond, -atom is -hybridized while in graphite, atom is hybridized.
-Bond angle of is less then due to presence of lone pair of electron on oxygen.
--bond are only formed only when -bond is already formed.
- Sigma bond is formed by head on overlapping and -bond is formed by lateral or sideways overlapping.
-In , the atom is hybridized.