Al₂S₃

Definition

Al₂S₃, or aluminum sulfide, is an ionic compound composed of two aluminum atoms and three sulfur atoms. It is an important compound in the context of ionic and molecular compounds, as it demonstrates the principles of ionic bonding and the formation of polyatomic ions.

5 Must Know Facts For Your Next Test

1. The chemical formula Al₂S₃ indicates that the compound is composed of two aluminum atoms and three sulfur atoms.
2. Aluminum has an oxidation number of +3, while sulfur has an oxidation number of -2 in this compound.
3. The ionic bonds in Al₂S₃ are formed between the positively charged aluminum ions (Al³⁺) and the negatively charged sulfide ions (S²⁻).
4. The sulfide ion (S²⁻) is a polyatomic ion, as it is a charged group of atoms that behaves as a single unit.
5. Al₂S₃ is an example of an ionic compound, where the strong electrostatic forces between the oppositely charged ions hold the compound together.

Review Questions

• Explain how the oxidation numbers of aluminum and sulfur determine the formation of the ionic compound Al₂S₃.
  • The oxidation number of aluminum is +3, meaning that each aluminum atom has a charge of 3+. The oxidation number of sulfur is -2, meaning that each sulfur atom has a charge of 2-. To balance the charges and form a neutral compound, two aluminum atoms (with a total charge of 6+) combine with three sulfur atoms (with a total charge of 6-), resulting in the ionic compound Al₂S₃.
• Describe the role of polyatomic ions in the formation of ionic compounds like Al₂S₃.
  • In the compound Al₂S₃, the sulfur atoms form a polyatomic ion, the sulfide ion (S²⁻). Polyatomic ions are charged groups of two or more atoms that behave as a single unit. The presence of the sulfide ion (S²⁻) allows it to bond with the positively charged aluminum ions (Al³⁺) to form the ionic compound Al₂S₃. The combination of the polyatomic sulfide ion and the aluminum ions demonstrates how ionic compounds can be formed through the interaction of oppositely charged species.
• Evaluate the importance of understanding the principles of ionic bonding and polyatomic ions in the context of the compound Al₂S₃.
  • Understanding the principles of ionic bonding and polyatomic ions is crucial in the context of the compound Al₂S₃ because it allows us to predict the compound's structure, properties, and behavior. By recognizing that Al₂S₃ is an ionic compound formed through the attraction of positively charged aluminum ions and negatively charged sulfide ions, we can infer that it will have characteristics typical of ionic compounds, such as high melting and boiling points, and the ability to conduct electricity when molten or in aqueous solution. Additionally, the presence of the polyatomic sulfide ion (S²⁻) highlights the importance of considering the behavior of charged groups of atoms, rather than just individual elements, when studying ionic and molecular compounds.

Related terms

Ionic Bonding:

Ionic bonding is the electrostatic attraction between oppositely charged ions, which occurs when atoms transfer electrons from one to another, forming positively and negatively charged ions.

Polyatomic Ion:

A polyatomic ion is a charged group of two or more atoms that behave as a single unit, such as the sulfate ion (SO₄²⁻) or the carbonate ion (CO₃²⁻).

Oxidation Number:

The oxidation number is the charge that an atom would have in a compound if the electrons in the compound were transferred completely, according to a set of rules.