Bonds & ions
Covalent bond — সমযোজী বন্ধন
Quick answer
A covalent bond is a shared pair of electrons holding two nonmetal atoms together, as in the O–H bonds of water.
Definition
A covalent bond forms when two nonmetal atoms, neither willing to hand electrons over entirely, share one or more pairs of electrons so both can count the pair toward a full outer shell. One shared pair makes a single bond, two pairs make a double bond (), three pairs a triple bond (). Covalent compounds usually exist as molecules with fairly low boiling points, and they generally do not conduct electricity because no free ions or electrons wander about.
For example
In every water molecule the oxygen atom shares one electron pair with each of the two hydrogen atoms, so one drop of rain is a vast crowd of such joined atoms.