IB Chemistry Standard Level (SL) Practice Exam

The term for a negative ion that gains electrons is an anion. When a neutral atom gains one or more electrons, it results in a net negative charge because the number of negatively charged electrons exceeds the number of positively charged protons in the nucleus. This process typically occurs with nonmetals, which have a higher electron affinity and tend to accept electrons to achieve a more stable electronic configuration, often resembling that of noble gases.

For example, a chlorine atom (Cl) can gain an electron to become a chloride ion (Cl⁻), exhibiting how atoms become anions through the gain of electrons. Understanding the characteristics of anions is essential in various chemical contexts, including ionic bonding and the behavior of substances in solutions.