Once magnesium (Mg) gives up electron(s) to become an ion, it will become (Hint - it gives up electrons. What would happen to an onion that gives up layers?) * A.) a cation that is larger than the original atom
B.) a cation that is smaller than the original atom
C.) an anion that is smaller than the original atom

B.) a cation that is smaller than the original atom

Explanation:

When the atoms of an element gains or loses electrons, it becomes charged. This charged atom is called an ION. An ion can either be a CATION or ANION depending on whether the atom loses electrons to become positively charged (cation) or gains electrons to become negatively charged (anion).

In this case, magnesium (Mg) atom gives up or loses electron(s) to become an ion, it will become positively charged and hence called a CATION. However, since it loses electrons in its atom, it becomes SMALLER than the original magnesium atom. This is because the electrons left in the atom becomes more attracted to the nucleus and decreases the ionic radius.