Question

Name the following compounds and assign oxidation states to the halogens in them: (a) \(\mathrm{Co}\left(1 \mathrm{O}_{3}\right)_{3},\) (b) \(\mathrm{Ca}\left(1 \mathrm{O}_{4}\right)_{2}\), (c) \(\mathrm{PF}_{6}^{-},(\mathbf{d}) \mathrm{ICl}_{4}^{-}\), (e) \(\mathrm{HBrO},\) (f) AtH.

Short answer

The names of the given compounds are (a) Cobalt(III) Iodate, (b) Calcium Periodate, (c) Hexafluorophosphate ion, (d) Tetrachloroiodate ion, (e) Hypobromous acid, and (f) Astatine Hydride. The oxidation states of the halogens in each compound are: (a) Iodine: +5, (b) Iodine: +7, (c) Fluorine: -1, (d) Iodine: +3 and Chlorine: -1, (e) Bromine: +1, and (f) Astatine: -1.

Step-by-step solution

Naming each compound

(a) \(\mathrm{Co}\left(1 \mathrm{O}_{3}\right)_{3}\): This compound contains Cobalt (Co) and the polyatomic ion IO₃⁻ which is Iodate. So, the name of the compound is Cobalt(III) Iodate. (b) \(\mathrm{Ca}\left(1 \mathrm{O}_{4}\right)_{2}\): This compound contains Calcium (Ca) and the polyatomic ion IO₄⁻ which is Periodate. So, the name of the compound is Calcium Periodate. (c) \(\mathrm{PF}_{6}^{-}\): This compound contains Phosphorus (P) and Fluorine (F) with a -1 charge. The name of this compound is Hexafluorophosphate ion. (d) \(\mathrm{ICl}_{4}^{-}\): This compound contains Iodine (I) and Chlorine (Cl) with a -1 charge. The name of this compound is Tetrachloroiodate ion. (e) \(\mathrm{HBrO}\): This compound contains Hydrogen (H), Bromine (Br), and Oxygen (O). The name of this compound is Hypobromous acid. (f) AtH: This compound contains Hydrogen (H) and Astatine (At). The name of this compound is Astatine Hydride.

Determine the oxidation states for halogens

(a) \(\mathrm{Co}\left(1 \mathrm{O}_{3}\right)_{3}\): Here, the halogen is Iodine (I). To determine its oxidation state, we use some of the rules for oxidation states: 1. The sum of the oxidation states in a neutral compound is 0. 2. The oxidation state of oxygen in most compounds is -2. IO₃⁻ oxidation states: I + 3(-2) = -1 I = +5, so the oxidation state of Iodine in this compound is +5. (b) \(\mathrm{Ca}\left(1 \mathrm{O}_{4}\right)_{2}\): In this compound, the halogen is again Iodine (I). IO₄⁻ oxidation states: I + 4(-2) = -1 I = +7, so the oxidation state of Iodine in this compound is +7. (c) \(\mathrm{PF}_{6}^{-}\): In this compound, the halogen is Fluorine (F). PF₆⁻ oxidation states: P + 6(F) = -1 Since the oxidation state of F in compounds is always -1: P + 6(-1) = -1 P = +5, thus the oxidation state of Fluorine in this compound is -1. (d) \(\mathrm{ICl}_{4}^{-}\): Here, the halogens are Iodine (I) and Chlorine (Cl). ICl₄⁻ oxidation states: I + 4(Cl) = -1 Since the oxidation state of Cl in compounds is usually -1: I + 4(-1) = -1 I = +3, so the oxidation state of Iodine in this compound is +3, and the oxidation state of Chlorine is -1. (e) \(\mathrm{HBrO}\): In this compound, the halogen is Bromine (Br). HBrO oxidation states: H + Br + O = 0 Using standard oxidation states for H (+1) and O (-2), +1 + Br - 2 = 0 Br = +1, thus the oxidation state of Bromine in this compound is +1. (f) AtH: In this compound, the halogen is Astatine (At). AtH oxidation states: At + H = 0 Using standard oxidation states for H (+1), At + 1 = 0 At = -1, so the oxidation state of Astatine in this compound is -1.

Key concepts

Chemical Nomenclature

Chemical nomenclature is a systematic way of naming chemical compounds. The goal is to provide a clear, unambiguous name for every chemical substance. The nomenclature is essential for communicating chemical compositions and reactions accurately.

For inorganic compounds like the ones in the exercise, the IUPAC naming system is commonly used. This system takes into account the elements in a compound and their quantities to generate a name:

• Ionic compounds often have names composed of the cation followed by the anion's name.
• Ternary compounds, those containing three different elements, are often named with a root and a suffix like '-ate' or '-ite' to indicate different oxidation states or the presence of oxygen.

By knowing the rules of chemical nomenclature, you can name compounds like Cobalt(III) Iodate or Hypobromous Acid based on the components and their oxidation states.

Getting familiar with polyatomic ions, their standard names, and common oxidation states is key to mastering chemical nomenclature.

Halogens

Halogens are a group of elements found in Group 17 of the periodic table. They include fluorine, chlorine, bromine, iodine, and astatine. These elements are known for their high reactivity and tendency to form salts when combined with metals.

Some important characteristics of halogens include:

• High electronegativity: This means halogens readily attract electrons in reactions.
• Existence as diatomic molecules in nature (e.g., F₂, Cl₂)
• Variety in physical states at room temperature, from gaseous (fluorine, chlorine) to solid (iodine, astatine)

In compounds, halogens typically form negative ions (halides) like Cl⁻, F⁻, due to their tendency to gain an electron to achieve a stable octet configuration. Understanding the properties and behaviors of halogens is crucial when predicting their behavior in chemical reactions.

Iodine Compounds

Iodine is a halogen that is often found in both organic and inorganic compounds. In the context of inorganic chemistry, iodine can form several interesting compounds with varying oxidation states.

In the exercises, we encounter compounds like Iodate ( ext{IO}_{3}^{-}) and Periodate ( ext{IO}_{4}^{-}). The oxidation state of iodine in these compounds is +5 and +7, respectively, which reflects its ability to form compounds with multiple oxygen atoms.

• Iodate and Periodate are examples of oxyanions, where iodine is bonded to oxygen atoms.
• Iodine's versatility allows it to adopt oxidation states ranging from -1 in iodides to higher positive states in oxoanions.

When naming iodine compounds, it’s important to recognize the number and type of atoms bonded to iodine, as it directs the compound's name and formula.

Phosphorus Compounds

Phosphorus is a versatile element that forms a wide range of compounds, including oxides, acids, and halides. In the exercise, we look into the compound Hexafluorophosphate ion ( ext{PF}_{6}^{-}) where phosphorus is in a high oxidation state of +5.

Some features of phosphorus compounds include:

• Phosphorus forms either positive or neutral oxidation states (+3, +5) in many compounds.
• It commonly bonds with oxygen, hydrogen, and halogens.
• In halogenated forms, it is often paired with highly electronegative elements like fluorine.

Understanding phosphorus's chemical behavior aids in predicting compound formation and reactivity. Knowing about phosphorus halides and other compounds can enhance comprehension of its role within chemical reactions and industrial applications.