A charged atom is called an ion. Ions are formed when an atom gains or loses electrons, resulting in an unequal number of protons and electrons.
When an atom loses one or more electrons, it becomes positively charged because the number of protons (positively charged particles) in the nucleus is greater than the number of electrons (negatively charged particles) surrounding it. This type of ion is called a cation. For example, if a sodium atom (Na) loses one electron, it forms a sodium cation (Na+).
On the other hand, when an atom gains one or more electrons, it becomes negatively charged because the number of electrons is now greater than the number of protons. This type of ion is called an anion. For instance, if a chlorine atom (Cl) gains one electron, it forms a chloride anion (Cl-).
Ions play a crucial role in chemical reactions and the formation of compounds. They can attract or repel other ions or polar molecules due to their electrical charges, leading to various chemical interactions and reactions.