Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

How is a covalent bond formed?

1. By the transfer of electrons between two atoms

2. By sharing one or more pairs of electrons between atoms

3. By the electrostatic attraction of charged ions

4. By the repulsion of electrons

The correct answer is: By sharing one or more pairs of electrons between atoms

A covalent bond is formed through the sharing of one or more pairs of electrons between two atoms. This type of bond occurs when atoms have similar electronegativities, which means they have a comparable tendency to attract electrons. Instead of completely transferring electrons as seen in ionic bonds, atoms involved in covalent bonding share electrons to achieve a more stable electron configuration, typically resembling that of noble gases. The shared electrons allow each atom to attain a filled outer shell, which leads to greater stability. For example, in a water molecule, each hydrogen atom shares an electron with the oxygen atom, resulting in a covalent bond that is crucial for the molecule's structure and properties. This process contrasts with transferring electrons, which would lead to ionic bonds, or the attraction of charged ions that characterizes ionic bonding. Repulsion of electrons does not contribute to bond formation; instead, it is the attraction between the shared electrons and the nuclei of the atoms that stabilizes the bond. Thus, the correct answer highlights the unique characteristic of covalent bonding as collaborative sharing rather than transfer or repulsion.