Ionic vs. Covalent Compound Classification Generator

You write chemical bonding classification drills for a chemistry class that recently moved past memorizing the periodic table and into predicting how atoms connect. Most students can recite the electronegativity difference cutoffs. Fewer of them remember to check whether a metal is even present before applying those cutoffs, and that is exactly where this practice set is aimed.

Generate [PROBLEM_COUNT:number:3-10] classification problems at a [DIFFICULTY:select:basic,advanced] level. At the basic level, give me the two elements directly, like sodium and chlorine or nitrogen and oxygen, so the only task is classifying the bond between them. At the advanced level, give me a full compound formula instead, like MgCl2 or CO2, so I have to identify which elements are present before I can classify anything, and include at least one formula per set with three or more elements so I have to isolate the relevant bond type instead of assuming the whole compound is one uniform type.

For every pair, walk through the same method in order: check whether a metal and a nonmetal are both present, which points to ionic bonding through electron transfer, or whether both elements are nonmetals, which points to covalent bonding through electron sharing. Where I give you or you know an electronegativity difference for the pair, use it as a secondary check: below about 0.4 is nonpolar covalent, roughly 0.4 to 1.7 is polar covalent, and above about 1.7 usually signals ionic character. State the electronegativity values you are using when you cite this check, instead of naming a category with no number behind it.

Treat the metal-plus-nonmetal rule as the primary test, not the electronegativity gap alone, and say so explicitly whenever the two tests could point in different directions. Hydrogen and fluorine have a large electronegativity difference, over 1.7 by some tables, yet the bond is polar covalent and not ionic, because both elements are nonmetals and neither one gives up an electron completely. Flag any pair in the set where the electronegativity gap alone would mislead a student who skipped the metal check, and explain why the metal check overrides it.

In [ANSWER_MODE:select:worked answers inline after each problem,separate answer key at the end], for an advanced formula problem, first list every element the formula contains and whether each one is a metal or a nonmetal, then apply the classification method to the relevant pair, then state the final classification on its own line. For a basic element-pair problem, skip straight to applying the method since the elements are already given.

If I give you two elements or a formula where the classification is a real toss-up, such as two elements with very close electronegativity values, say so directly and explain what makes it a toss-up instead of forcing a clean answer where chemistry itself does not give one.