1) The attractive force that holds two or more ions together in a molecule or ion is called chemical bond.
2) Atoms are combining to form molecules for two reasons. They are:-
i) To reduce energy :- every system of universe tends to lose potential energy and becomes more stable. Its ability is proportional to 1 by energy.
ii)In a similar way when two atoms approach each other, forces of attraction and repulsion operate in between them.
iii) the forces of attraction are between the nucleus of one atom and the electrons of other atom.
3)The forces of repulsions are between two nuclei as well as on between the electrons of two atoms.
4) A chemical bond is said to be formed as the lowest energy.
5) Internal energy of molecule is less the sum of internal energies of individual atoms in that molecule.
EG:-In the formation of 1 mole of hydrogen .104k.cal of energy is released so hydrogen molecules are more stable than hydrogen atoms.
TYPES OF CHEMICAL BONDS:-
chemical bonds are formed by the rearrangement of the electrons present in the outer shell of the atoms. The arrangements involve loss or gain of electrons by the atoms of mutual sharing of electrons by the atom in attempt to attain the stable configuration of nearest noble gas.
Depending upon the mode of rearrangement of electrons the chemical bonds can be divided into three main categories.
covalent bond, double bond, triple bond.
Chemical bond formed by the transform of electrons from one atom to an another is called electrovalent or ionic bond.
the ionic bond is formed between metals and non metals.
The pair of electrons being shared by two atoms is called bond pair.