Final answer:
Calcium is slightly more reactive than Magnesium and will lose electrons more readily due to its position in the activity series and having a larger atomic radius than Magnesium, which results in a lower ionization energy.
Step-by-step explanation:
When comparing which metal will lose electrons more easily between Ca (Calcium) and Mg (Magnesium), we look at their tendencies to be oxidized. Calcium is an alkaline earth metal and is in group 2 of the periodic table, just like Magnesium. Both metals are quite active and have a strong tendency to lose their two valence electrons and form +2 cations. However, Magnesium has a slightly higher ionization energy (IE) because its atomic radius is smaller compared to Calcium. Therefore, Calcium will generally lose electrons more easily than Magnesium. This can also be understood by considering the activity series of metals, which places these two metals close to each other but with Calcium being slightly more reactive than Magnesium. Thus, in electrochemical reactions, you would expect Calcium to be oxidized before Magnesium.