Question

Why is the boiling point of iron higher than magnesium?

Answer 1

Let us first know what boiling the point of a substance is. The boiling point of a substance is that temperature at which the vapour pressure of a liquid becomes equivalent to the pressure surrounding the liquid and the transformation of a liquid into a vapour occurs. The boiling point of a liquid is affected by the atmospheric pressure of surroundings. The boiling point of a liquid at high pressure is higher than the boiling point of the same liquid at atmospheric pressure.

Complete answer:
In this case, we need to know that we must understand that Iron and Magnesium are both metals. The boiling point of any metal is determined by its hardness; as hardness increases, so does the boiling point; for example, the boiling point of aluminum is higher than that of Magnesium and higher than that of Sodium.
The number of valence electrons in a metal determines its boiling point; as this number increases, the strength of the metallic bond between metal atoms increases, hardness increases, and boiling point increases.
Iron is a transition metal, which means it has a greater melting and boiling temperature and is recognized for its availability of valence electrons.
Thus, the boiling point of iron is higher than that of magnesium.

Note:
It must be noted that the normal boiling point of a liquid (also known as the atmospheric boiling point or atmospheric pressure boiling point) is the special case where the liquid's vapour pressure equals the stated atmospheric pressure at sea level, one atmosphere. Since $1982$ IUPAC has defined the standard boiling point as the temperature at which boiling occurs at one bar of pressure.