Final answer:
MgCl₂ is a solid at room temperature due to its ionic nature, formed when one magnesium atom combines with two chlorine atoms, balancing the charges to form a stable ionic compound with both ionic and covalent character influences.
Step-by-step explanation:
The compound MgCl₂ will be a solid at room temperature because it is an ionic compound. In MgCl₂, magnesium has a 2+ charge and chlorine has a 1- charge. To achieve a neutral compound, two chloride ions are needed to balance the 2+ charge of one magnesium ion, resulting in the formula MgCl₂. Ionic compounds like MgCl₂ are typically solids at room temperature due to their strong ion-ion interactions which generate high melting points. However, because bonds in ionic compounds have some covalent character, the melting point can be influenced. Specifically, MgCl₂ has a lower percent ionic character compared to NaCl, with covalent bonding contributing to a melting point that is lower than expected for a purely ionic compound. In the formation of MgCl₂ from its elements, a reaction occurs where Mg atoms lose two electrons to form Mg²⁺ ions and Cl atoms gain an electron to become Cl⁻ ions, illustrating the transfer of electrons characteristic of ionic bond formation.