Problem 34 - Chemistry: The Central Science in SI Units, Global Edition

Question

Name the following compounds and assign oxidation states to the halogens in them: (a) \(\mathrm{BCl}_{3}\), (b) \(\mathrm{Sr}\left(\mathrm{IO}_{4}\right)_{2}\), (c) \(\mathrm{LiOCl}\) (d) \(\mathrm{HClO}\) (e) \(\mathrm{CuClO}\) (f) \(\mathrm{Mg}\left(\mathrm{IO}_{2}\right)\).

Step-by-Step Solution

Answer

The compounds and their corresponding oxidation states of the halogens are as follows: (a) Boron trichloride (BCl3), chlorine has an oxidation state of -1. (b) Strontium periodate (Sr(IO4)2), iodine has an oxidation state of +7. (c) Lithium hypochlorite (LiOCl), chlorine has an oxidation state of +1. (d) Hypochlorous acid (HClO), chlorine has an oxidation state of +1. (e) Copper(I) chlorate (CuClO), chlorine has an oxidation state of +5. (f) Magnesium iodite (Mg(IO2)), iodine has an oxidation state of +3.

Step 1: (a) Naming and oxidation state of halogen in BCl3)

For the compound BCl3, the name is boron trichloride. The oxidation state of chlorine in boron trichloride is -1.

Step 2: (b) Naming and oxidation state of halogen in Sr(IO4)2)

For the compound Sr(IO4)2, the name is strontium periodate. The oxidation state of iodine in strontium periodate is +7.

Step 3: (c) Naming and oxidation state of halogen in LiOCl)

For the compound LiOCl, the name is lithium hypochlorite. The oxidation state of chlorine in lithium hypochlorite is +1.

Step 4: (d) Naming and oxidation state of halogen in HClO)

For the compound HClO, the name is hypochlorous acid. The oxidation state of chlorine in hypochlorous acid is +1.

Step 5: (e) Naming and oxidation state of halogen in CuClO)

For the compound CuClO, the name is copper(I) chlorate. The oxidation state of chlorine in copper(I) chlorate is +5.

Step 6: (f) Naming and oxidation state of halogen in Mg(IO2))

For the compound Mg(IO2), the name is magnesium iodite. The oxidation state of iodine in magnesium iodite is +3.

Key Concepts

Naming Compounds

Understanding how compounds are named forms the foundation of chemistry. Chemical names indicate the elements involved and, sometimes, their ratios. A systematic approach is used to ensure scientists worldwide can understand each other. Generally, the name is composed of the name of the central atom followed by the names of the other atoms it is bonded to. Often, these are represented by a prefix to indicate the number of atoms present.
For example:

• In boron trichloride (\(\mathrm{BCl}_{3}\)), the prefix 'tri' suggests there are three chlorine atoms.
• For strontium periodate (\(\mathrm{Sr}\left(\mathrm{IO}_{4}\right)_{2}\)), the term 'periodate' refers to the IO4 group.

The suffixes such as '-ide', '-ate', or '-ite' refer to the specific composition and oxidation state of the molecule. By understanding these naming conventions, scientists can predict the compound's structure and properties.

Halogens

Halogens are elements found in Group 17 of the periodic table, known for their reactivity. They include fluorine, chlorine, bromine, iodine, and astatine. These elements are highly electronegative and often form salts with metals.
In chemistry, halogens are also involved in various oxidation states depending on the compound they form.

• In boron trichloride (\(\mathrm{BCl}_{3}\)), chlorine is in the -1 oxidation state.
• In hypochlorous acid (\(\mathrm{HClO}\)), the oxidation state of chlorine is +1.
• In strontium periodate (\(\mathrm{Sr}\left(\mathrm{IO}_{4}\right)_{2}\)), iodine exhibits an oxidation state of +7.

Understanding the oxidation states of halogens is crucial for determining the properties and behavior of compounds within chemical reactions.

Periodic Table Elements

The periodic table is a scientific chart that organizes elements based on their atomic structure and properties. Each element is represented by a unique symbol and arranged in groups (columns) and periods (rows). The position of an element in the periodic table helps predict its chemical behavior and reactivity.
Elements like strontium and iodine are part of different groups on the periodic table.

• Strontium, in Group 2, is an alkaline earth metal known for forming stable divalent ions, such as in strontium periodate (\(\mathrm{Sr}\left(\mathrm{IO}_{4}\right)_{2}\)).
• Iodine, part of the halogens in Group 17, often exhibits multiple oxidation states as seen in the compounds listed in the exercise.

Grouping elements this way allows scientists to understand relationships between them and predict how they will interact within chemical reactions. The periodic table is a fundamental tool in understanding chemical compounds and their reactions.