Question

Give the names and charges of the cation and anion in each of the following compounds: (a) \(\mathrm{CuS}\), (b) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}\), (c) \(\mathrm{Al}\left(\mathrm{ClO}_{3}\right)_{3}\), (d) \(\mathrm{Co}(\mathrm{OH})_{2}\), (e) \(\mathrm{PbCO}_{3}\).

Short answer

The cations and anions, along with their charges, in the given compounds are: a) CuS: Copper(II) (+2) and Sulfide (-2) b) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}\): Silver(I) (+1) and Sulfate (-2) c) \(\mathrm{Al}\left(\mathrm{ClO}_{3}\right)_{3}\): Aluminum (+3) and Chlorate (-1) d) \(\mathrm{Co}(\mathrm{OH})_{2}\): Cobalt(II) (+2) and Hydroxide (-1) e) \(\mathrm{PbCO}_{3}\): Lead(II) (+2) and Carbonate (-2)

Step-by-step solution

Identify the Elements

Cu (Copper) is a metal and S (Sulfur) is a non-metal. In a compound, the metal forms a cation and the non-metal forms an anion.

Determine the Charges

Copper (Cu) can have charges of either +1 or +2, and Sulfur (S) has a charge of -2. In this case, since there is one Sulfur atom, the charge of Copper must be +2.

Name the Cation and Anion

The cation is Copper(II) and the anion is Sulfide. Their charges are +2 and -2, respectively. #b) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}\)#

Identify the Elements

Ag (Silver) is a metal and SO4 (Sulfate) is a polyatomic anion.

Determine the Charges

Silver (Ag) always has a charge of +1, and SO4 (Sulfate) has a charge of -2.

Name the Cation and Anion

The cation is Silver(I), and the anion is Sulfate. Their charges are +1 and -2, respectively. #c) \(\mathrm{Al}\left(\mathrm{ClO}_{3}\right)_{3}\)#

Identify the Elements

Al (Aluminum) is a metal, and ClO3 (Chlorate) is a polyatomic anion.

Determine the Charges

Aluminum (Al) has a charge of +3, and Chlorate (ClO3) has a charge of -1.

Name the Cation and Anion

The cation is Aluminum, and the anion is Chlorate. Their charges are +3 and -1, respectively. #d) \(\mathrm{Co}(\mathrm{OH})_{2}\)#

Identify the Elements

Co (Cobalt) is a metal, and OH (Hydroxide) is a polyatomic anion.

Determine the Charges

Cobalt (Co) can have charges of either +2 or +3 in compounds, and Hydroxide (OH) has a charge of -1. In this case, since there are two OH groups, the charge of Cobalt must be +2.

Name the Cation and Anion

The cation is Cobalt(II), and the anion is Hydroxide. Their charges are +2 and -1, respectively. #e) \(\mathrm{PbCO}_{3}\)#

Identify the Elements

Pb (Lead) is a metal, and CO3 (Carbonate) is a polyatomic anion.

Determine the Charges

Lead (Pb) can have charges of either +2 or +4, and Carbonate (CO3) has a charge of -2. In this case, since there is one Carbonate group, the charge of Lead must be +2.

Name the Cation and Anion

The cation is Lead(II), and the anion is Carbonate. Their charges are +2 and -2, respectively.

Key concepts

Cation Identification

In chemical nomenclature, identifying cations is crucial for naming compounds. A cation is a positively charged ion, which typically forms from a metal losing electrons.
Metals such as Copper (Cu), Aluminum (Al), and Cobalt (Co) usually act as cations.
For example:

• Copper can form Copper(I) or Copper(II), depending on whether it loses one or two electrons, resulting in a +1 or +2 charge respectively.
• Aluminum consistently forms a +3 cation since it loses three electrons.

Recognizing the correct cation and its charge is necessary for determining the proper name and ensuring balance in the chemical formula.

Anion Identification

Anions are negatively charged ions formed when non-metals gain electrons. Identifying anions is essential to understanding the compound structure.
Sulfide (S²⁻), formed from Sulfur, is an example of a simple non-metal anion.
Non-metals receive electrons to gain a negative charge. This leads to their formation as anions in compounds.
Recognizing these anions helps in combining them with cations to create neutral compounds.

Polyatomic Ions

Polyatomic ions are charged entities composed of multiple atoms. Unlike simple ions, these consist of a group of atoms bonded together with an overall charge. Examples include:

• Sulfate (SO₄²⁻)
• Chlorate (ClO₃⁻)
• Hydroxide (OH⁻)
• Carbonate (CO₃²⁻)

These ions interact with cations to form various compounds. Understanding their formation and charge is key to chemical nomenclature, as it influences the name and characteristics of the compound.

Metal and Non-Metal Compounds

Compounds formed from metals and non-metals involve ionic bonds, where electrons are transferred from the metal to the non-metal. The result is the formation of ions, which combine to make a neutral compound.
For instance,

• Copper(II) sulfide (CuS)
• Silver sulfate (Ag₂SO₄)
• Aluminum chlorate (Al(ClO₃)₃)
• Cobalt(II) hydroxide (Co(OH)₂)

These compounds show the combination of metals acting as cations and non-metals or polyatomic ions acting as anions.
By understanding these interactions, one can determine the proper formula and charge balance within the compound, ensuring a correctly named and constructed chemical structure.