Problem 128 - Chemistry An Atoms First Approach

Question

What do each of the following sets of compounds/ions have in common? a. \(\mathrm{SO}_{3}, \mathrm{NO}_{3}^{-}, \mathrm{CO}_{3}^{2-}\) b. \(\mathrm{O}_{3}, \mathrm{SO}_{2}, \mathrm{NO}_{2}^{-}\)

Step-by-Step Solution

Answer

In set a (\(\mathrm{SO}_{3}, \mathrm{NO}_{3}^{-}, \mathrm{CO}_{3}^{2-}\)), the compounds/ions have three oxygen atoms in their formulas and are all oxyanions (sulfite, nitrate, and carbonate anions). In set b (\(\mathrm{O}_{3}, \mathrm{SO}_{2}, \mathrm{NO}_{2}^{-}\)), the common feature is that they all have two oxygen atoms in their formulas, representing ozone, sulfur dioxide, and the nitrite anion.

Step 1: Set a: \(\mathrm{SO}_{3}, \mathrm{NO}_{3}^{-}, \mathrm{CO}_{3}^{2-}\)

Upon examination, the common feature among these compounds/ions is that they all have three oxygen atoms in their formulas. Additionally, they are all oxyanions, meaning they are anions in which an element is bonded to one or more oxygen atoms. Specifically, these are the sulfite, nitrate, and carbonate anions.

Step 2: Set b: \(\mathrm{O}_{3}, \mathrm{SO}_{2}, \mathrm{NO}_{2}^{-}\)

Upon closer inspection, the common feature in this second set of compounds/ions is that they all have two oxygen atoms in their formulas. Specifically, these are ozone, sulfur dioxide, and the nitrite anion.

Key Concepts

Chemical Formulas

Chemical formulas are the shorthand used by scientists to describe the composition of a compound. They list the elements present in the compound, followed by numbers written as subscripts that indicate the number of atoms of each element in the molecule. For example, in the formula \(\mathrm{CO}_{3}^{2-}\), 'C' stands for carbon, 'O' stands for oxygen, and the subscript '3' indicates that there are three oxygen atoms present. The superscript '2-' indicates that the compound carries a charge, specifically a negative two charge, which leads us to the concept of anions.

Understanding chemical formulas is crucial as they provide a wealth of information about the substance, including its chemical composition and the ratio of atoms within the molecule. This is especially helpful for students tackling exercises in chemistry, as interpreting these formulas accurately can enable better understanding of the reactions and compounds being studied.

Oxygen Atoms in Compounds

Oxygen is one of the most abundant elements and it forms a variety of compounds, including oxides and oxyanions. In oxyanions, oxygen is usually bonded to another element called the central atom. For example, in sulfate \(\mathrm{SO}_{3}\) and nitrate \(\mathrm{NO}_{3}^{-}\), 'S' and 'N' are the central atoms, respectively, each bonded to three oxygen atoms. This configuration can impact the properties and reactivity of the oxyanion.

It's important to note that the number of oxygen atoms can influence the name of the anion; sulfite \(\mathrm{SO}_{3}^{2-}\) and sulfate \(\mathrm{SO}_{4}^{2-}\) are distinct due to the differing number of oxygen atoms. This pattern is consistent across various elements and their corresponding oxyanions, which is why recognizing the pattern in oxygen atoms helps in identifying and naming these compounds.

Anions

Anions are negatively charged ions, which form when an atom or molecule gains electrons. In the context of oxyanions, these are negatively charged ions that contain oxygen. For instance, nitrate \(\mathrm{NO}_{3}^{-}\) and carbonate \(\mathrm{CO}_{3}^{2-}\) each carry a negative charge as seen in their chemical formulas.

The charge on the anion contributes to the compound's overall stability and reactivity. The rules governing the naming of anions include adding the suffix '-ate' or '-ite' to the central atom based on the number of oxygen atoms present. A higher number of oxygen atoms typically correspond to the '-ate' suffix, while a lower number corresponds to the '-ite' suffix. Thus, recognizing anions by their chemical formulas, charges, and adherence to naming rules is essential for mastering the chemical aspects of oxyanions.