Question

In which of the following pairs is the name incorrect? Give the correct name for the formulas indicated. a. \(\mathrm{Ag}_{2} \mathrm{O},\) disilver monoxide b. \(\mathrm{N}_{2} \mathrm{O},\) dinitrogen monoxide c. \(\mathrm{Fe}_{2} \mathrm{O}_{3},\) iron(II) oxide d. \(\mathrm{PbO}_{2}\), plumbous oxide e. \(\mathrm{Cr}_{2}\left(\mathrm{SO}_{4}\right)_{3},\) chromium(III) sulfate

Short answer

The incorrect names are in options a, c, and d. The correct names for these compounds are: a. Silver(I) oxide c. Iron(III) oxide d. Lead(IV) oxide

Step-by-step solution

Analyzing Ag2O

Since Silver (Ag) has a fixed oxidation number of +1 and Oxygen (O) has an oxidation number of -2, we can write the correct formula as Ag2O. Therefore, the given formula is correct.

Checking name for Ag2O

Disilver monoxide is an incorrect name. The correct name is Silver(I) oxide. --b--

Analyzing N2O

We have two Nitrogen (N) atoms and one Oxygen (O) atom in this formula. Both N and O have fixed oxidation numbers. Given these oxidation numbers, the given formula is correct.

Checking name for N2O

The given name, dinitrogen monoxide, is correct for N2O. --c--

Analyzing Fe2O3

Iron (Fe) has variable oxidation numbers, and Oxygen (O) has a fixed oxidation number. We can have Fe2O3 written as the correct formula for this compound.

Checking name for Fe2O3

The given name, iron(II) oxide, is incorrect. The correct name is Iron(III) oxide. --d--

Analyzing PbO2

Lead (Pb) has variable oxidation numbers, and Oxygen (O) has a fixed oxidation number. We can have PbO2 written as the correct formula for this compound.

Checking name for PbO2

The given name, plumbous oxide, is incorrect. The correct name is Lead(IV) oxide. --e--

Analyzing Cr2(SO4)3

Chromium (Cr) has variable oxidation numbers, and SO4 has a fixed oxidation number. We can have \(Cr_{2}(SO_{4})_{3}\) written as the correct formula for this compound.

Checking name for Cr2(SO4)3

The given name, chromium(III) sulfate, is correct for \(Cr_{2}(SO_{4})_{3}\). In summary, the incorrect names are found in compounds a, c, and d. The correct names should be Silver(I) oxide, Iron(III) oxide and Lead(IV) oxide, respectively.

Key concepts

Oxidation States

An oxidation state, also known as an oxidation number, is a way to keep track of electrons in atoms during chemical reactions. This concept is crucial to understanding how elements combine to form compounds. Oxidation states help us determine how many electrons are being shared, lost, or gained in a compound.

• Positive oxidation states indicate a loss of electrons.
• Negative oxidation states imply a gain of electrons.

For example, in the formula \(\text{Ag}_2\text{O}\), silver (Ag) typically has an oxidation number of +1 and oxygen (O) typically has an oxidation number of -2. Understanding oxidation states helps in figuring out the correct names for compounds. In the case of silver oxide, the correct name would be Silver(I) oxide, not "disilver monoxide."
This naming mistake arises from misinterpreting the oxidation states of the elements involved.

Chemical Formulas

Chemical formulas are shorthand representations of compounds. They use symbols from the periodic table and numerical subscripts to convey information about the kinds and numbers of atoms present in a substance. Understanding chemical formulas is essential in chemistry, as they communicate the composition of molecules and compounds.

• Elements in the formula are written using their symbols.
• Subscripts following an element indicate how many atoms of that element are present.

For instance, in \(\text{Fe}_2\text{O}_3\), the formula tells us there are two iron (Fe) atoms and three oxygen (O) atoms. This specific formula represents a compound commonly known as Iron(III) oxide, due to the +3 oxidation state of iron in this compound. Misunderstanding the chemical formula or its components can lead to errors in naming, like calling it "iron(II) oxide," which incorrectly suggests a different oxidation state.

Ionic Compounds

Ionic compounds are chemical compounds composed of ions held together by electrostatic forces known as ionic bonding. These compounds form when metals transfer electrons to non-metals, resulting in positively charged ions (cations) and negatively charged ions (anions). Understanding the nature of ionic compounds is key to grasping their chemical behavior.

• Cations are typically metals that lose electrons.
• Anions are typically non-metals that gain electrons.

In \(\text{PbO}_2\), lead (Pb) can lose four electrons, forming a cation with a +4 charge, while each oxygen atom gains two electrons each, forming the oxide anion. This results in the compound being called Lead(IV) oxide rather than "plumbous oxide."
The understanding of ionic compounds and their nomenclature allows us to correctly write and interpret chemical formulas, preventing errors in identification and communication of chemical substances.