The metallic bond in magnesium is stronger than that in calcium because magnesium has a

The metallic bond is a type of chemical bond that occurs between metal atoms. It arises due to the electrostatic attraction between the positively charged metal ions and the delocalized electrons surrounding them. The strength of the metallic bond depends on various factors, including the size of the metal atom and the number of valence electrons it has. In this case, the correct option is "smaller atomic size." Magnesium has a smaller atomic size than calcium, which means that the distance between the metal ions in magnesium is smaller than that in calcium. The closer the metal ions are to each other, the stronger the metallic bond will be. This is because the attraction between the positively charged metal ions and the negatively charged delocalized electrons is stronger when the ions are closer together. Therefore, since magnesium has a smaller atomic size than calcium, the metallic bond in magnesium is stronger than that in calcium. It is important to note that the option "greater number of valence electrons" is not correct in this case. Although the number of valence electrons can also affect the strength of the metallic bond, it is not the main factor that determines the difference in the strength of the metallic bond between magnesium and calcium.