Final answer:
The cation formed from magnesium in magnesium iodate is the magnesium ion (Mg2+), which is a divalent cation with a +2 charge.
Step-by-step explanation:
The cation ion formed from magnesium in magnesium iodate is a magnesium ion, which is represented as Mg2+. Magnesium, being in group 2 of the periodic table, tends to lose two electrons to achieve the electron configuration of the nearest noble gas, which in this case is neon. This loss of electrons results in the formation of a divalent cation with a +2 charge.
When magnesium combines with elements such as iodine, it will donate its two valence electrons leading to the formation of the Mg2+ ion. Meanwhile, the iodate anion (IO3-) is formed when iodine bonds with oxygen atoms. Together, magnesium cation and iodate anion can form the compound magnesium iodate, where magnesium strictly acts as the cationic part of the compound.
Finally, it is worth remembering that cations are generally named by taking the element name and adding the word 'ion'. Hence, we refer to this ion simply as a magnesium ion.