Question

Write the chemical formula for the following binary compounds given their constituent ions: (a) aluminum bromide, \(\mathrm{Al}^{3+}\) and \(\mathrm{Br}^{-}\) (b) cadmium sulfide, \(\mathrm{Cd}^{2+}\) and \(\mathrm{S}^{2-}\) (c) manganese(II) phosphide, \(\mathrm{Mn}^{2+}\) and \(\mathrm{P}^{3-}\) (d) lead(IV) fluoride, \(\mathrm{Pb}^{4+}\) and \(\mathrm{F}\)

Short answer

(a) \( \mathrm{AlBr}_3 \), (b) \( \mathrm{CdS} \), (c) \( \mathrm{Mn}_3\mathrm{P}_2 \), (d) \( \mathrm{PbF}_4 \).

Step-by-step solution

Determine Aluminum Bromide Formula

For aluminum bromide, the ions involved are \( \mathrm{Al}^{3+} \) and \( \mathrm{Br}^{-} \). To balance the charges, three bromide ions are needed to neutralize one aluminum ion. This gives the formula: \( \mathrm{AlBr}_3 \).

Determine Cadmium Sulfide Formula

For cadmium sulfide, the ions are \( \mathrm{Cd}^{2+} \) and \( \mathrm{S}^{2-} \). The charges are already balanced with a 1:1 ratio, so the formula is \( \mathrm{CdS} \).

Determine Manganese(II) Phosphide Formula

Here, the ions are \( \mathrm{Mn}^{2+} \) and \( \mathrm{P}^{3-} \). To balance the charges, we need three \( \mathrm{Mn}^{2+} \) ions for every two \( \mathrm{P}^{3-} \) ions, giving the formula: \( \mathrm{Mn}_3\mathrm{P}_2 \).

Determine Lead(IV) Fluoride Formula

For lead(IV) fluoride, \( \mathrm{Pb}^{4+} \) and \( \mathrm{F}^{-} \) are involved. Four fluoride ions are needed to balance one lead ion, resulting in the formula: \( \mathrm{PbF}_4 \).

Key concepts

Binary Compounds

Binary compounds are simple chemical compounds that consist of two different elements. These compounds form from the combination of metals and non-metals or two non-metals. Binary compounds are prevalent in chemistry as they lay the fundamental building blocks for more complex molecules. When writing the chemical formula for binary compounds, such as aluminum bromide or cadmium sulfide, it's crucial to consider the constituents involved.

• Binary compounds usually end with the suffix "-ide" as seen in compounds like bromide and sulfide.
• The order for writing a binary compound's formula is typically metal first, followed by the non-metal.

This simple yet systematic approach helps to clearly define the composition of a compound, aiding in understanding its chemical behavior and properties.

Ion Charges

Ion charges are an essential aspect of understanding how binary compounds form. Ions are atoms or molecules that have gained or lost electrons and thus carry a charge. Metal atoms tend to lose electrons and become positive ions, also known as cations. Conversely, non-metal atoms gain electrons to become negatively charged ions or anions.

• In aluminum bromide, the aluminum ion is represented as \(\mathrm{Al}^{3+}\), showing it has lost three electrons.
• Bromide is written as \(\mathrm{Br}^{-}\), indicating it has gained one electron.
• To create a neutral compound, the positive and negative charges must balance.

Understanding ion charges is pivotal for determining the correct stoichiometry of a compound, ensuring the charges from each ion cancel out.

Chemical Balancing

Chemical balancing is an important technique employed to create stable binary compounds. For a chemical formula to be correct, the total charges of the cations must equal the total charges of the anions, resulting in a neutral compound. This principle ensures the law of conservation of charge is respected.

• For example, in lead(IV) fluoride, one \(\mathrm{Pb}^{4+}\) ion pairs with four \(\mathrm{F}^{-}\) ions to balance to zero charge, making the formula \(\mathrm{PbF}_4\).
• In manganese(II) phosphide, three \(\mathrm{Mn}^{2+}\) ions balance with two \(\mathrm{P}^{3-}\) ions, resulting in \(\mathrm{Mn}_3\mathrm{P}_2\).

Practicing chemical balancing ensures accurate representation of a substance and provides insight into the possible proportions of elements in a compound.

Chemistry Education

Chemistry education makes the abstract world of molecules and reactions accessible through clear, step-by-step learning strategies. Learning to write chemical formulas aids in developing critical thinking and enhances problem-solving skills. In educational settings, focusing on core concepts like binary compounds, ion charges, and chemical balancing offers a foundational understanding vital for more advanced studies in chemistry.

• Encouraging hands-on practice with exercises similar to the binary compound examples enriches comprehension.
• Discussing mistakes and common pitfalls, such as not balancing charges correctly, helps solidify learning.

Thus, chemistry education empowers students to decipher the language of chemicals by transforming theoretical understanding into practical knowledge.