Fill in name and empirical formula of each ionic compound that can be formed from ions below: 1) Cation: Na+, Anion: IO2^- 2) Cation: Na+, Anion: IO4^- 3) Cation: Na+, Anion: IO3^- 4) Cation: Na+, Anion: IO-
The Correct Answer and Explanation is:
Ionic Compounds Formed from Na⁺ and Iodine Oxyanions
| No. | Cation | Anion | Name of Compound | Empirical Formula |
|---|---|---|---|---|
| 1 | Na⁺ | IO₂⁻ | Sodium iodite | NaIO₂ |
| 2 | Na⁺ | IO₄⁻ | Sodium periodate | NaIO₄ |
| 3 | Na⁺ | IO₃⁻ | Sodium iodate | NaIO₃ |
| 4 | Na⁺ | IO⁻ | Sodium hypoiodite | NaIO |
Explanation:
When forming ionic compounds, cations and anions combine in ratios that result in overall electrical neutrality. In this case, sodium ion (Na⁺) is a monovalent cation, meaning it carries a single positive charge. It can combine with any monovalent anion, such as the oxyanions of iodine, which also carry a single negative charge (⁻1). Because the charges are equal and opposite, these ions combine in a 1:1 ratio, resulting in empirical formulas of the form NaIOₓ, where x depends on the number of oxygen atoms in the polyatomic ion.
The iodine oxyanions are named systematically based on the number of oxygen atoms bonded to the iodine atom:
- IO⁻ is called hypoiodite. The prefix “hypo-” and suffix “-ite” indicate fewer oxygen atoms than the “-ite” form.
- IO₂⁻ is iodite, the “-ite” form with fewer oxygens than “-ate”.
- IO₃⁻ is iodate, the common “-ate” form.
- IO₄⁻ is periodate, using the prefix “per-” and suffix “-ate” to denote the most oxygen-rich form.
When these anions combine with Na⁺, their names are prefixed by “sodium” (the cation name), and the empirical formula reflects the 1:1 stoichiometry. These naming conventions are standard for ionic compounds involving polyatomic ions and help ensure consistent communication in chemistry.
