Final answer:
It is easier for Mg to lose 2 valence electrons to form Mg²+ than to gain 6 more, due to the energetic favorability of losing valence electrons that leads to a stable octet configuration.
Step-by-step explanation:
It is easier for Mg to lose 2 valence electrons than to gain 6 more to be full. Magnesium (Mg) is located in Group 2A of the periodic table and has two valence electrons. For Mg to reach a stable configuration, it aims to achieve an octet, which is more energetically favorable by losing two electrons to form a Mg²+ cation rather than gaining six electrons due to the large energy requirement to add electrons to an already positively charged nucleus. Losing one electron to form Mg+ does not achieve an octet, making it an unlikely stable ion. Magnesium typically forms compounds like magnesium chloride (MgCl₂) by transferring two electrons to two chlorine atoms, each gaining one electron to also complete their octet, leading to a stable electron configuration. The process of removing the first two electrons occurs at a significantly lower energy level compared to removing the third, as indicated by ionization energy trends. Electrons within atoms are grouped in such a way that the second ionization energy (IE) is typically greater than the first, while the third IE is considerably larger since it requires removing an electron from a lower energy subshell (2p), which is more energetically costly.