Question

What is a covalent bond? How does it differ from an ionic bond?

Answer 1

A covalent bond is a region of high electron density BETWEEN two positively charged atomic nuclei.........

Explanation:

Traditionally, covalent bonding is regarded as the sharing of (a pair of) electrons between nuclei. The region of high electron density allows close approach of a pair of positively charged atomic nuclei. The equilibrium distance which maximizes electrostatic attraction between the electron cloud and the nuclei, and MINIMIZES nuclear repulsion is also known as the covalent bond length. For simple, homonuclear diatomic molecules, such as `H_2`, or `He_2`, or `F_2` the level of theoretical explanation, and agreement with experimental result, is relatively high.

On other hand, ionic bonding is conceived to result from the transfer of electrons between atoms to give discrete positive and negative ions:

`Na(g) + 1/2Cl_2(g) rarrNa^(+)Cl^(-)(s)darr`

The individual ions are arrayed in an interlocking, non-molecular lattice, in which electrostatic attraction between unlike charges is of greater magnitude that electrostatic repulsion between like charges, and a net attractive force, the lattice enthalpy, results.