Question

Write formulas for the compounds formed from the element on the left and each of the elements on the right. (a) Li N, O, F (b) \(\mathrm{Ba} \quad \mathrm{N}, \mathrm{O}, \mathrm{F}\) (c) \(\mathrm{Al} \quad \mathrm{N}, \mathrm{O}, \mathrm{F}\)

Short answer

\((a) \text{Li}_3\text{N}, \text{Li}_2\text{O}, \text{LiF}; \quad (b) \text{Ba}_3\text{N}_2, \text{BaO}, \text{BaF}_2; \quad (c) \text{AlN}, \text{Al}_2\text{O}_3, \text{AlF}_3.\)

Step-by-step solution

Determine the Charges

First, identify the valency of each element. Lithium (Li) has a valency of +1, Barium (Ba) has a valency of +2, and Aluminum (Al) has a valency of +3. Nitrogen (N) typically has a valency of -3, Oxygen (O) has a valency of -2, and Fluorine (F) has a valency of -1.

Write Formulas for Lithium Compounds

To balance the charges and write the chemical formulas for lithium compounds, combine Li with N, O, and F. For Li and N, the formula is \(\text{Li}_3\text{N}\) since three Li ions with +1 charge each will balance one N ion with a -3 charge. For Li and O, the formula is \(\text{Li}_2\text{O}\) because two Li ions will balance one O ion. For Li and F, the formula is \(\text{LiF}\), as one Li ion will balance one F ion.

Write Formulas for Barium Compounds

Barium has a +2 charge, so we need to balance it with the charges of N, O, and F. For Ba and N, the formula is \(\text{Ba}_3\text{N}_2\) because 3 Ba ions will balance 2 N ions. For Ba and O, the formula is \(\text{BaO}\) since one Ba ion will balance one O ion. For Ba and F, the formula is \(\text{BaF}_2\) because one Ba ion will balance two F ions.

Write Formulas for Aluminum Compounds

Aluminum has a +3 charge, which needs to be balanced with N, O, and F. For Al and N, the formula is \(\text{AlN}\) because one Al ion will balance one N ion. For Al and O, the formula is \(\text{Al}_2\text{O}_3\) as two Al ions will balance three O ions. For Al and F, the formula is \(\text{AlF}_3\) because one Al ion will balance three F ions.

Key concepts

Valency and Ionic Charge

Valency is a fundamental concept that relates to the combining power of an element. It reflects the ability of an atom to bond with other atoms by losing, gaining, or sharing electrons. When atoms lose or gain electrons, they form ions with a positive or negative charge, known as ionic charge.

Take lithium (Li) for instance, which has a valency of +1. It means lithium can lose one electron and become a positively charged ion, Li+. Nitrogen (N), on the other side, has a valency of -3, indicating that it tends to gain three electrons, forming a negatively charged ion, N^3-.

When writing chemical formulas for compounds, it's crucial to balance the total positive and negative charges. We achieve a neutral compound when the sum of the charges equals zero. For example, to pair lithium (Li⁺) and nitrogen (N^3-), we need three lithium ions to balance one nitrogen ion, resulting in the formula \( \text{Li}_3\text{N} \). Understanding valency and ionic charge is essential for correctly writing chemical formulas and comprehending the stability of compounds.

Chemical Compound Nomenclature

The nomenclature of chemical compounds is a systematic method of naming chemical substances. Each part of a compound's name provides information about its composition and structure. The naming process varies slightly depending on whether the compound is ionic or covalent.

In the context of ionic compounds, names are derived from the cation (positive ion) followed by the anion (negative ion). The cation is named first and retains the name of the element, for instance, lithium in lithium fluoride. The anion is named by taking the root of the element's name and adding the suffix '-ide', such as fluoride for fluorine.

For the exercises provided, the compound formed by barium (Ba) and oxygen (O) is named barium oxide, and its formula is \( \text{BaO} \). The correct naming reflects both the elements involved and their ratios, which are determined by their valencies and ionic charges, ensuring clarity and precision in chemical communication.

Balancing Chemical Equations

Balancing chemical equations is the process of ensuring that the number of atoms for each element involved in a reaction is the same on both the reactants and products sides. This practice adheres to the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.

While writing chemical formulas requires balancing charges, balancing chemical equations involves a different skill. It includes adjusting coefficients—the numbers placed before a compound's formula—to balance the atoms. For example, if we have a simple synthesis reaction where aluminum (Al) reacts with oxygen (O₂) to form aluminum oxide, we must ensure the number of aluminum and oxygen atoms is the same on both sides.

The balanced equation would look like \(4\text{Al} + 3\text{O}_2 \rightarrow 2\text{Al}_2\text{O}_3\), indicating that four aluminum atoms react with three molecules of oxygen (each containing two oxygen atoms) to produce two formula units of aluminum oxide, which each contain two aluminum and three oxygen atoms. Balancing equations is a fundamental skill for any chemistry student as it provides deeper insight into the quantitative aspects of reactions.