Question

Elements in the same group of the periodic table often form oxyanions with the same general formula. The anions are also named in a similar fashion. Based on these observations,suggest a chemical formula or name, as appropriate, for each of the following ions:$(\mathbf{a}){\mathrm{BrO}}_4^{-},(\mathbf{b}){\mathrm{SeO}}_3^{2-}$ $(\mathbf{c})$ arsenate ion, $(\mathbf{d})$ hydrogen tellurate ion.

Short answer

The chemical formula and names for the given ions are as follows: a) BrO₄⁻: Perbromate ion b) SeO₃²⁻: Selenite ion c) Arsenate ion: AsO₄³⁻ d) Hydrogen tellurate ion: HTeO₃⁻ (Hydrogen Tellurite Ion)

Step-by-step solution

Analyzing Given Ions

Let's start with the first ion BrO₄⁻. In this case, the central element is Bromine (Br) from group 17 (halogens) and is combined with four Oxygen atoms (O) with a total charge of -1. It is called Perbromate ion. Next, we have SeO₃²⁻ where the central atom is Selenium (Se) from group 16 (chalcogens) combined with three Oxygen atoms, overall with a charge of -2. This ion is called Selenite ion.

Finding the Formula for Arsenate Ion

Arsenate ion has Arsenic (As) as the central element. Arsenic belongs to group 15 (pnictogens), below Nitrogen and Phosphorus. As Phosphate ion (PO₄³⁻) has a similar structure, we can assume that the formula for the arsenate ion would also follow the same pattern. Therefore, the arsenate ion (AsO₄) will also have a charge of -3, because like Phosphorus, Arsenic needs 3 more electrons to complete its octet. Thus, the chemical formula for the Arsenate ion becomes AsO₄³⁻.

Finding the Name for Hydrogen Tellurate Ion

The name indicates that there is one hydrogen atom joined with the tellurate ion. The central element in the tellurate ion is Tellurium (Te) from group 16 (chalcogens), same as Selenium. Since we know that the selenite ion has the formula SeO₃²⁻, we can infer that the tellurate ion will be TeO₃²⁻ because they are both in the same group. Now, we have to add a hydrogen atom to form the hydrogen tellurate ion. When a hydrogen atom (with +1 charge) binds to the tellurate ion (TeO₃²⁻), the overall charge will become -1. Thus, the name for hydrogen tellurate ion with the formula HTeO₃⁻ is "Hydrogen Tellurite Ion".

Key concepts

Periodic Table Groups

Understanding periodic table groups is essential for grasping why certain elements form specific oxyanions. Elements in the same group often exhibit similar chemical behavior because of their similar valence electron configurations.

For example, elements in group 17, known as halogens, often form oxyanions with similar formulas. Bromine (Br), when forming the perbromate ion (BrO₄⁻), follows a pattern seen in other halogens like chlorine (ClO₄⁻). This regularity helps predict chemical behaviors and formulas.

• Group 15 (pnictogens): Includes elements like nitrogen and phosphorus, known for forming oxyanions with a -3 charge, such as arsenate (AsO₄³⁻).
• Group 16 (chalcogens): Includes oxygen, sulfur, and selenium, forming oxyanions usually with a -2 charge, like selenite (SeO₃²⁻).
• Group 17 (halogens): Known for different oxyanion structures, as seen with perbromate (BrO₄⁻).

Understanding these group similarities simplifies predicting chemical formulas and ion nomenclature.

Chemical Formula

A chemical formula represents the elements in a compound and shows the ratio of atoms. For oxyanions, these formulas help indicate the type and number of atoms involved, as well as the charges.

The formula for perbromate, BrO₄⁻, reveals a structure where bromine is central, surrounded by four oxygens. This is analogous to how other elements in the same group arrange with oxygen.

Similarly, the formula SeO₃²⁻ for selenite shows selenium centrally bonded to three oxygens. Utilizing this formula pattern aids in predicting structures like that of arsenate (AsO₄³⁻), where arsenic takes the place similar to phosphorus in phosphate (PO₄³⁻).

• Formulas highlight electron sharing or transfer that define ion charges.
• Common patterns in formulas emerge from periodic table groups.
• Predictive value: Knowledge of similar structure in group elements aids in determining unknown oxyanion formulas.

These formulas form a foundation in studying chemical bonding and reactions.

Ion Nomenclature

Ion nomenclature is the system used for naming ions, providing insight into their composition and charge. Accurate naming can guide chemical understanding and predict reactions.

The name 'perbromate' indicates a specific oxyanion series, with -ate endings typically signifying a higher number of oxygen atoms compared to -ite endings. In the perbromate ion, BrO₄⁻, 'per-' indicates even more oxygen than a standard bromate.

Selenite, SeO₃²⁻, uses the -ite suffix to signify fewer oxygens than selenate (SeO₄²⁻). Understanding these naming conventions reveals the balance between oxygen and the central atom.

• Suffixes like -ite and -ate help identify oxygen atom count.
• Prefixes like per- (more oxygen) and hypo- (less oxygen) highlight variations within the same element.
• Hydrogen added to oxyanions, as in hydrogen tellurite (HTeO₃⁻), shifts the charge, adding complexity to nomenclature.

Mastering these naming rules aids in effective communication of chemical identities.