Iodine is a non-metal with an atomic number of 53. In its outer shell, it has seven electrons, which means it is just one electron short of a complete octet, a stable electron configuration. Because of this, iodine tends to gain an electron when forming an ion.
When an iodine atom gains an electron, it becomes negatively charged. The most common ion formed by iodine is the iodide ion (I–). This ion has a full outer shell with eight electrons, achieving a more stable configuration.
In summary, iodine is more likely to gain electrons, forming an iodide ion (I–), rather than lose electrons.