Distinguish the difference between the two types of ions. Describe ion formation using electron configurations. Predict ionic charge. Ions As seen in prior sections, atoms contain a nucleus with neutrons and positively charged protons, surrounded by negatively charged electrons. In an atom, the total number of electrons, negative charge, equals the total number of protons, positive charge, and therefore, atoms are electrically neutral or uncharged. If an atom loses or gains electrons, it will become a positively or negatively charged particle, called an ion . The loss of one or more electrons results in more protons than electrons and an overall positively charged ion , called a cation . For example, a sodium atom with one less electron is a cation, Na + , with a +1 charge (Figure \(\PageIndex{1}\)). When an atom gains one or more electrons, it becomes a negatively charged a nion , because there are more electrons than protons. When chlorine gains one electron it forms a chloride ion, Cl – , with a –1 charge (Figures \(\PageIndex{2}\)) The names for positive and negative ions are pronounced CAT-eye-ons (cations) and ANN-eye-ons (anions), respectively. Key Takeaways Ions can be positively charged or negatively charged. Ionic charge relates to valence electrons and valence shells. Exercises What are the two types of ions? When the following atoms become ions, what charges do they acquire? Li S Ca F 4. Identify each as a cation, an anion, or neither. H + Cl − O 2 Ba 2 + CH 4 CS 2 5. Identify each as a cation, an anion, or neither. NH 3 Br − H − Hg 2 + CCl 4 SO 3 Answers Cations (positive charged) and anions (negative charged) 1+ 2− 2+ 1− 4. cation anion neither cation neither neither 5. neither anion anion cation neither neither Contributors Lisa Sharpe Elles, University of Kansas