Question

Assign an oxidation number to each atom in the following compounds: (a) \(\mathrm{SnCl}_{4}\) (b) \(\mathrm{CrO}_{3}\) (c) \(\mathrm{VOCl}_{3}\) (d) \(\mathrm{V}_{2} \mathrm{O}_{3}\) (e) \(\mathrm{HNO}_{3}\) (f) \(\mathrm{FeSO}_{4}\)

Short answer

Sn: +4, Cl: -1; Cr: +6, O: -2; V: +5, O: -2, Cl: -1; V: +3, O: -2; H: +1, N: +5, O: -2; Fe: +2, S: +6, O: -2.

Step-by-step solution

Determine Oxidation Numbers for SnCl4

In the compound \(\mathrm{SnCl}_{4}\), chlorine (Cl) typically has an oxidation number of -1. Since there are four Cl atoms, their total contribution is -4. To ensure the compound's total charge is zero, the oxidation number of Sn (tin) must be +4. Thus, Sn: +4, Cl: -1 each.

Determine Oxidation Numbers for CrO3

In \(\mathrm{CrO}_{3}\), oxygen (O) typically has an oxidation number of -2. With three O atoms, the total is -6. To balance this, Cr must have an oxidation number of +6. Thus, Cr: +6, O: -2 each.

Determine Oxidation Numbers for VOCl3

In \(\mathrm{VOCl}_{3}\), oxygen (O) is -2, and chlorine (Cl) is -1 each. With one O and three Cl, the total negative charge is -5. To balance this, vanadium (V) must have an oxidation number of +5. Thus, V: +5, O: -2, Cl: -1 each.

Determine Oxidation Numbers for V2O3

In \(\mathrm{V}_{2}\mathrm{O}_{3}\), each oxygen (O) has an oxidation number of -2, so three O atoms contribute -6 in total. Since there are two vanadium (V) atoms, to balance the -6, each V must have an oxidation number of +3. Thus, V: +3 each, O: -2 each.

Determine Oxidation Numbers for HNO3

In \(\mathrm{HNO}_{3}\), hydrogen (H) is typically +1, and oxygen (O) is -2. With three O atoms, their total is -6. To balance H's +1 and the -6 from O, nitrogen (N) must be +5. Thus, H: +1, N: +5, O: -2 each.

Determine Oxidation Numbers for FeSO4

In \(\mathrm{FeSO}_{4}\), oxygen (O) is -2 with four O atoms totaling -8. Sulfur (S) is usually +6 in sulfate (\(\mathrm{SO}_{4}^{2-}\)), totaling +6. To balance the overall neutral charge, iron (Fe) must be +2. Thus, Fe: +2, S: +6, O: -2 each.

Key concepts

Chemical Compounds

Chemical compounds are substances consisting of two or more elements chemically bonded together. In each compound, the atoms are bound in fixed ratios and distinct chemical structures. This often determines their physical and chemical properties. There are three primary types of chemical compounds:

• Ionic Compounds: Formed by the transfer of electrons from one atom to another, typically between a metal and a non-metal. This results in positive and negative ions that attract each other.
• Covalent Compounds: These are created by the sharing of electron pairs between atoms, usually non-metals.
• Metallic Compounds: Involve a "sea of electrons" that are shared among a lattice of metal atoms, contributing to properties like conductivity.

Each type of compound has unique characteristics. Understanding these helps to predict their chemical behavior and interactions in reactions such as oxidation.

Redox Reactions

Redox reactions, short for reduction-oxidation reactions, are chemical reactions that involve the transfer of electrons between two substances. These reactions are fundamental in various processes, from industrial applications to biological systems.

In a redox reaction:

• Oxidation: Refers to the loss of electrons from an element or compound, increasing its oxidation state.
• Reduction: Involves the gain of electrons, decreasing the oxidation state.

The species that loses electrons is oxidized, while the one that gains electrons is reduced. To identify and balance these reactions, you must determine the oxidation numbers of elements in a compound. Understanding oxidation numbers is key to predicting the direction and stoichiometry of redox reactions.

Chemical Bonding

Chemical bonding is the force that holds atoms together in a compound, dictating how atoms are arranged and how they interact. Here's a closer look at the types of chemical bonds:

• Ionic Bonds: Formed when an atom donates one or more electrons to another atom, resulting in oppositely charged ions. This bond is generally strong and occurs in salts like NaCl.
• Covalent Bonds: Occur when atoms share pairs of electrons, resulting in molecules or polymers. These can be single, double, or triple bonds based on the number of shared electron pairs.
• Metallic Bonds: Involve a free-moving "sea of electrons" in metals, contributing to properties like malleability and electrical conductivity.

Understanding the type of bonding in a compound is integral to comprehending its reactivity, physical state, and properties such as melting and boiling points.

Inorganic Chemistry

Inorganic chemistry is the study of inorganic compounds, typically those not involving carbon-hydrogen bonds. It covers a broad area of substances like salts, metals, minerals, and gases. This field explores various areas, including:

• Elements and Compounds: Focuses on the properties, structures, and reactions of all elements in the periodic table except organic compounds.
• Coordination Chemistry: Investigates complex compounds formed by transition metals bonded to ligands, which could be ions, metal atoms, or simple molecules like water.
• Crystallography: Studies the arrangement of atoms within crystals to understand the material's properties.

In studying inorganic chemistry, using concepts such as oxidation numbers and understanding bond types help chemists predict reactions and design new compounds for various applications.