Final answer:
A covalent bond is formed through the sharing of electrons between atoms. These bonds can be single, double, or triple, based on the number of electrons shared. Nonpolar covalent bonds result from equal sharing of electrons, while polar covalent bonds occur when electrons are shared unequally.
Step-by-step explanation:
A bond that involves the sharing of electrons is a covalent bond. This type of bond forms when two atoms, either of the same or different elements, share electrons to complete their valence shells. In a simple example, a single covalent bond, such as in hydrogen gas (H-H), each hydrogen atom shares its single electron, resulting in a pair of electrons being shared. This sharing allows both hydrogen atoms to achieve a stable electron configuration.
In a covalent bond, atoms can share different numbers of electrons. When two electrons are shared, it's known as a single bond, four electrons shared between two atoms constitute a double bond, and six electrons shared form a triple bond. The shared pairs of electrons are usually represented as lines between the bonded atoms. For instance, in a water molecule (H2O), the electrons are shared between the hydrogen atoms and the oxygen atom, although they are pulled more towards the more electronegative oxygen atom.
Covalent bonding can be further classified based on the electronegativity difference between the bonded atoms. When this difference is small or zero, such as in Cl2, the electrons are shared equally, forming a nonpolar covalent bond. However, when there is a moderate difference, as seen in an H-Cl bond, the electrons are not shared equally, leading to a polar covalent bond.