Potassium nitrate is built from K+ ions and NO3- ions. Which bond types are present in the solid?

1. Start inside the nitrate ion, where nitrogen and oxygen are bonded to each other. 2. Nitrogen and oxygen are both nonmetals, so those bonds are covalent, and the electronegativity gap makes them polar. 3. Now step outside the ion and look at the whole compound. 4. The nitrate ion carries a full negative charge and the potassium ion a full positive charge. 5. Those two full charges attract electrostatically, which is an ionic bond. 6. So both bond types are present at once, one inside the polyatomic ion and one between the ions. 7. Answering ionic only misses the covalent bonding hidden inside the nitrate ion. 8. Answering polar covalent only ignores the full charges that hold the crystal together. _Source: OpenStax Chemistry (CC BY 4.0), Chs 7 and 17, section 7.2 Covalent Bonding_