Arizona State University (ASU) BIO201 Human Anatomy and Physiology I Exam 1 Practice

In a polar covalent bond, the unequal sharing of electrons between two atoms leads to the development of partial positive and negative charges at either end of the bond. This charge separation creates a dipole, which is characterized by a positive end and a negative end. The presence of these charges means that one atom has a slightly positive charge because it is less electronegative and holds the electrons more loosely, while the other atom, which is more electronegative, has a slightly negative charge due to its higher attraction for the shared electrons.

The concept of a dipole is crucial in understanding molecular polarity and how molecules interact with each other, especially in terms of physical properties like boiling points and solubility. In contrast, a cation and anion are terms used to describe positively and negatively charged ions, respectively, which arise from complete electron transfers, not from the sharing of electrons as seen in covalent bonding. An ionic pair refers to a full ionic bond formed between these charged ions rather than a polar covalent bond where the charge distribution is partial. Therefore, the correct identification of a dipole in a polar covalent bond emphasizes the nature of the charge distribution within the molecule.