Final answer:
The size criteria for forming a solid solution between two elements depends on the similarity of the atomic radii and the stoichiometries of the elements involved.
Step-by-step explanation:
The size criteria for forming a solid solution between two elements relates to the relative sizes of their ions and their stoichiometries. Similar ion sizes and stoichiometries allow different types of ionic compounds to crystallize in the same structure.
For elements to form solid solutions, their atomic radii should typically not differ by more than approximately 15%. This similarity in size is one factor that can lead to substituting one atom for another in the crystal lattice without disrupting the structure too much, therefore, aiding in the formation of a solid solution.
The size criteria for forming a solid solution between two elements is based on the relative sizes and stoichiometries (ratios of elements) of the ions in the compounds.
When the relative sizes of the ions and their stoichiometries are similar, different types of ionic compounds can crystallize in the same structure and form a solid solution. For example, if the ions have a 1:1 ratio and similar sizes, they are more likely to form a solid solution.