Here's how to determine the number of electrons in the iodide ion (I-):

* Start with the neutral atom: Iodine (I) has 53 electrons because its atomic number is 53.

* Consider the charge: The negative charge (1-) indicates that the ion has gained one extra electron.

* Add the extra electron: 53 (original electrons) + 1 (gained electron) = 54 electrons

Therefore, the iodide ion (I-) has 54 electrons.