WJEC Biology Practice Exam

Electronegativity is defined as a measure of the tendency of an atom to attract electrons when it forms a chemical bond with another atom. This property is crucial in understanding how atoms interact with each other, particularly in covalent bonds where atoms share electrons. Higher electronegativity values indicate a stronger attraction for electrons, which influences the nature of the bond formed—whether it is covalent or ionic. For example, in molecules like water (H2O), oxygen has a higher electronegativity compared to hydrogen, leading to a polar covalent bond where the shared electrons are drawn closer to the oxygen atom. This results in a partial negative charge on the oxygen and a partial positive charge on the hydrogens, which greatly affects the molecule’s properties, including its polarity and hydrogen bonding capabilities. Understanding electronegativity is fundamental in predicting molecular behavior and reactivity, making choice C the correct answer to the SAMPLEquestion about its definition.