The ion I–, which is the iodide ion, has a total of 53 protons and 54 electrons. This occurs because the iodide ion is formed when an iodine atom gains one electron.
To break it down:
- An iodine atom has an atomic number of 53, which means it has 53 protons in its nucleus.
- In its neutral state, an iodine atom also has 53 electrons orbiting around the nucleus, equal to the number of protons.
- However, when iodine gains an electron to become I–, it now has 54 electrons and still retains its 53 protons.
Thus, the difference between the number of protons and electrons in I– is what gives it a negative charge, making it an anion.