Question

Elements in the same family often form oxyanions of the same general formula. The anions are named in a similar fashion. Give the names of the oxyanions of selenium and tellurium: \(\mathrm{ScO}_{4}^{2-}, \mathrm{SeO}_{3}^{2-}, \mathrm{TeO}_{4}^{2-}, \mathrm{TeO}_{3}^{2-}\)

Short answer

The oxyanions of selenium and tellurium are named as follows: 1. \(\mathrm{SeO}_{3}^{2-}\): Selenite 2. \(\mathrm{ScO}_{4}^{2-}\): Selenate (The correct formula should be \(\mathrm{SeO}_{4}^{2-}\)) 3. \(\mathrm{TeO}_{4}^{2-}\): Tellurate 4. \(\mathrm{TeO}_{3}^{2-}\): Tellurite

Step-by-step solution

Understand the naming convention for oxyanions

Oxyanions are polyatomic anions containing oxygen and another element (in this case, selenium or tellurium). The naming conventions for oxyanions are based on the number of oxygen atoms and the charge of the anion: 1. If the anion has one less oxygen atom than the common oxyanion, the anion's name ends with -ite. 2. If the anion has the same number of oxygen atoms as the common oxyanion, the anion's name ends with -ate. Now, let's find the names of the given oxyanions.

Name the oxyanions of selenium

We have two oxyanions for selenium: \(\mathrm{SeO}_{3}^{2-}\) and \(\mathrm{ScO}_{4}^{2-}\). For \(\mathrm{SeO}_{3}^{2-}\): As it has less number of oxygen atoms than \(\mathrm{ScO}_{4}^{2-}\) and both have the same charge, the name will end with -ite. Therefore, the name for \(\mathrm{SeO}_{3}^{2-}\) is selenite.

Name the oxyanions of tellurium

We have two oxyanions for tellurium: \(\mathrm{TeO}_{4}^{2-}\) and \(\mathrm{TeO}_{3}^{2-}\). For \(\mathrm{TeO}_{4}^{2-}\): As it has more number of oxygen atoms than \(\mathrm{TeO}_{3}^{2-}\) and both have the same charge, the name will end with -ate. Therefore, the name for \(\mathrm{TeO}_{4}^{2-}\) is tellurate. For \(\mathrm{TeO}_{3}^{2-}\): As it has less number of oxygen atoms than \(\mathrm{TeO}_{4}^{2-}\) and both have the same charge, the name will end with -ite. Therefore, the name for \(\mathrm{TeO}_{3}^{2-}\) is tellurite. In conclusion, the names of the oxyanions of selenium and tellurium are as follows: 1. \(\mathrm{SeO}_{3}^{2-}\): Selenite 2. \(\mathrm{ScO}_{4}^{2-}\): Selenate (The correct formula should be \(\mathrm{SeO}_{4}^{2-}\)) 3. \(\mathrm{TeO}_{4}^{2-}\): Tellurate 4. \(\mathrm{TeO}_{3}^{2-}\): Tellurite

Key concepts

Polyatomic Ions

Polyatomic ions are charged species composed of two or more atoms covalently bonded, or of a metal complex that can be considered to act as a single unit in the context of acid and base chemistry or in the formation of salts. These ions are prevalent in chemistry and play vital roles in the chemical formulas of compounds and their subsequent reactions.

Understanding how to identify and name polyatomic ions is an essential skill in chemistry. It's important to recognize that the overall charge on a polyatomic ion is not always determined by the number of electrons lost or gained by the element but is also affected by the number of oxygen atoms present. For instance, common polyatomic ions like sulfate \(\text{SO}_4^{2-}\) and nitrate \(\text{NO}_3^{-}\) have various atoms sharing the charge. The naming of these ions follows specific rules that help in identifying the composition and charge of the ion.

Chemical Nomenclature

Chemical nomenclature is the systematic naming of chemical compounds that allows chemists to communicate unambiguously about which substances they are referring to. For oxyanions, the nomenclature depends largely on the numbers of oxygen atoms present in the ion. If an oxyanion contains oxygen along with another element, the naming convention varies based on the relative number of oxygen atoms in the series.

Oxyanions with one less oxygen atom than the most common form are given an '-ite' suffix. If they have the most common or reference number of oxygen atoms, they receive an '-ate' suffix. Sometimes, there can even be a hypo- prefix for one less oxygen than the '-ite' form and a per- prefix for one more oxygen than the '-ate' form. Through this nomenclature, chemists can infer both composition and structure of the ions.

Anions of Selenium

Selenium is a nonmetal that forms multiple oxyanions, which are compounds of selenium bonded with oxygen. The anions of selenium typically follow the aforementioned nomenclature rules. For example, the \(\text{SeO}_3^{2-}\) ion, with one less oxygen atom relative to the most common selenium oxyanion \(\text{SeO}_4^{2-}\), is named 'selenite'. On the other hand, when selenium forms an oxyanion with the same number of oxygen atoms as the most common form, such as in \(\text{SeO}_4^{2-}\), the ion is named 'selenate'.

Remembering that the '-ate' suffix corresponds to a higher number of oxygen atoms can help avoid confusion when moving between the different types of selenium oxyanions.

Anions of Tellurium

Similar to selenium, tellurium also forms various oxyanions. The two main oxyanions of tellurium discussed here are tellurite \(\text{TeO}_3^{2-}\) and tellurate \(\text{TeO}_4^{2-}\). As per the nomenclature rules, tellurite has fewer oxygen atoms compared with tellurate, leading to the use of the '-ite' suffix. Conversely, tellurate has more oxygen atoms and thus carries the '-ate' suffix.

Recognizing the pattern between the suffixes '-ite' and '-ate' and the number of oxygen atoms is crucial for mastering the nomenclature of tellurium oxyanions, as well as for understanding the broader chemical properties these ions exhibit in different reactions and compounds.