Use this free practice quiz with 30 questions to review 07 Ionic and Covalent Bonding, test your knowledge, and prepare for your next test or exam.
A student claims that Al₂O₃ should have a 3:2 ratio because each Al³⁺ ion has a smaller subscript than each O²⁻ ion. Explain why this reasoning is incorrect. Show how the ion charges determine the neutral ratio, and clarify what the formula represents in the solid.
A laboratory sample of NaCl is tested first as a solid, then after melting, and then after dissolving in water. Predict which forms can conduct electricity and explain each prediction in terms of ion mobility.
A student labels KNO₃ simply as “an ionic compound” and concludes that it contains no covalent bonds. Correct the conclusion by identifying where each type of bonding occurs.
Compare the H–H and H–Cl bonds. For each, state whether electron sharing is equal or unequal and whether the bond is nonpolar or polar covalent. For H–Cl, identify which atom carries each partial charge and explain why.
Use the following hypothetical electronegativity values: A = 2.1, B = 2.5, C = 3.8, D = 2.6, and E = 3.0. Calculate ΔEN for A–B, C–D, and E–E; rank the bonds from smallest to largest difference; and explain what the ranking suggests about relative electron sharing. Do not assume a universal numerical cutoff between bond categories.
An introductory chart places an approximate boundary between polar covalent and ionic bonding at a particular ΔEN. A student says that a bond just above the boundary must be purely ionic and one just below it must be purely covalent. Explain why this conclusion is too absolute and how ΔEN should instead be used.
A graph of potential energy versus internuclear distance for two bonded atoms has a clear minimum. Explain how to identify the bond length from the graph and why a nearby distance that is not at the minimum is not the characteristic bond length.
A student claims that pulling two bonded atoms apart releases energy, while bringing two separated atoms together to form the bond requires energy. Identify and correct both errors using the energy changes associated with bond breaking and bond formation.
A model compares a single bond and a multiple bond between the same pair of atoms. State the expected general comparison in bond length and strength, then explain why this trend does not provide exact values for every chemical environment.
A molecular covalent substance has a relatively low melting point. A student concludes that its covalent bonds must be weak. Explain why that inference is not justified, distinguishing what usually separates during melting from what remains intact within each molecule.
Evaluate the statement, “Every ionic compound must have a higher melting and boiling point than every molecular covalent substance because covalent bonds are weak.” Identify what is broadly useful in the comparison, what is overstated, and why the explanation about covalent bonds is misleading.
A researcher compares how strongly two bonded atoms attract their shared electrons. In a separate experiment, the researcher measures the energy change when an isolated gaseous atom gains an electron. Name the concept relevant to each situation and explain how the concepts differ.
A chemical process breaks one covalent bond and later forms a different covalent bond. State the energy direction for each step, and explain whether the net energy change can be determined from that information alone.
Compare the bonds in H₂ and HCl. For each, describe how the shared electrons are distributed and classify the bond; for HCl, identify which atom is partially positive and which is partially negative.
A solid is modeled as containing M³⁺ and X²⁻ ions. Determine the simplest whole-number ratio that gives electrical neutrality, write the resulting formula, and explain what that formula represents in an ionic solid.
An ionic compound does not conduct electricity as a solid but can conduct when molten or dissolved in water. Explain both observations by describing the ions' mobility in each state.
Three hypothetical atoms have electronegativities A = 2.1, B = 2.5, and C = 3.4. Calculate the absolute electronegativity difference for A–B, A–C, and B–C. Which pair is expected to have the most unequal sharing and greatest ionic character, and which the most equal sharing and least ionic character? Explain what the comparison does and does not establish.
A student uses the same term for (1) an atom's attraction for shared electrons in a bond and (2) the energy change when an isolated gaseous atom gains an electron. Identify the correct term for each property and explain why they are not interchangeable.
For KNO₃, identify where ionic bonding occurs and where covalent bonding occurs. Explain how both bonding types can be present in the same compound without describing them as the same interaction.
A learner concludes that the covalent bonds inside a molecular substance must be weak because the substance melts at a relatively low temperature. Explain why this conclusion confuses two different kinds of interactions.
Explain why ionic compounds are generally high-melting solids. In your explanation, distinguish the structure of an ionic solid from a collection of discrete molecules and state whether the melting-point trend is absolute.
A student claims that one exact electronegativity-difference value universally separates every covalent bond from every ionic bond. Evaluate the claim using H–H, H–Cl, and Na–Cl, and explain how electronegativity difference should be used instead.
Two unfamiliar atom pairs are being assessed: one is metal–nonmetal and has a small electronegativity difference; the other is nonmetal–nonmetal and has a larger difference. For each pair, explain what the element types suggest, what the electronegativity difference suggests, and how the conflicting clues affect a cautious prediction about its bonding. Why do these clues not guarantee a perfectly ionic or perfectly covalent bond?
A confirmed ionic compound conducts electricity as a solid but not when molten. A confirmed molecular covalent substance has a higher melting point than a particular ionic solid. Compare these observations with the usual patterns for those substance types. What can you conclude from the observations, and what cause cannot be established from the general patterns alone?
A crystalline ionic solid contains ions X²⁺ and Y⁴⁻. Determine the smallest whole-number ratio of X ions to Y ions and write the formula. Show how the charges balance, then explain what the formula represents in the solid.
A student tests an ionic compound first as a solid and then after melting it. Predict whether it conducts electricity in each state, and explain the difference using the behavior of its ions.
Compare the bonds in H₂ and HCl. For each, describe how the bonding electrons are shared and classify the bond as nonpolar or polar covalent. For HCl, identify which atom is partially negative and which is partially positive, and explain how electronegativity difference helps account for the contrast.
Imagine comparing single, double, and triple bonds formed by the same pair of atoms in suitable chemical environments. Rank them from shortest to longest and from strongest to weakest. Explain what the strength ranking implies about the energy required to break each bond, and state an important limitation of these comparisons.
A molecular covalent substance has a relatively low melting point. A classmate concludes that its covalent bonds must be weak. Evaluate that conclusion by describing what typically separates during melting and what happens to the bonds within the molecules.
Analyze the bonding in potassium nitrate, KNO₃. Identify which interaction is ionic and which bonds are covalent, and explain how both bonding types can occur in the same compound without contradiction.