Question

Barium ions carry a \(2+\) charge, and nitrogen ions carry a 3 - charge. What would be the chemical formula for the ionic compound barium nitride?

Short answer

The chemical formula for barium nitride is \(\text{Ba}_3\text{N}_2\).

Step-by-step solution

Identify the Charges

Barium ions have a charge of \(2+\), which can be written as \(\text{Ba}^{2+}\). Nitrogen ions have a charge of \(3-\), which can be written as \(\text{N}^{3-}\).

Determine the Ratio of Ions

To balance the charges, we need to find the least common multiple of the absolute values of the charges. The least common multiple of 2 and 3 is 6.

Calculate the Number of Each Ion

We need three barium ions to reach a total positive charge of +6 (3 x \(2+\)) and two nitrogen ions to reach a total negative charge of -6 (2 x \(3-\)).

Write the Chemical Formula

Combine the ions in the ratio found in Step 3. Thus, the chemical formula is \(\text{Ba}_3\text{N}_2\), indicating three barium ions and two nitrogen ions.

Key concepts

Chemical Formula

A chemical formula is a way to express information about the proportions of atoms that constitute a particular chemical compound. It uses letters to represent elements and subscripts to indicate the number of each atom present. For ionic compounds, the formula reflects the smallest whole-number ratio of ions like cations and anions, ensuring the compound is neutral. The chemical formula is crucial for understanding how elements interact and the properties of the compound. For example, the formula \( ext{Ba}_3 ext{N}_2\) shows that in barium nitride, there are three atoms of barium (Ba) for every two atoms of nitrogen (N). The notation is clear and standardized, allowing chemists to easily share and communicate the structure of ionic compounds.

Cation and Anion Charges

Cations and anions are types of ions that differ based on their charge. Cations are positively charged ions, formed when an atom loses electrons. Conversely, anions are negatively charged ions, formed when an atom gains electrons. It's important to know the charges as they determine how ions combine to form compounds.

• **Cations**: These are usually metals, like barium (\(\text{Ba}^{2+}\)), which loses two electrons, resulting in a positive charge of 2+.
• **Anions**: These are often non-metals, such as nitrogen (\(\text{N}^{3-}\)), which gains three electrons, carrying a negative charge of 3-.

Understanding these charges is critical when predicting how elements combine in a compound and in ensuring the compound's electrical neutrality.

Balancing Charges in Compounds

Balancing charges is essential in forming stable ionic compounds. The idea is to ensure that the total positive charge from cations equals the total negative charge from anions, resulting in a compound with no overall charge.
To achieve this, consider the charges of the ions:

• Barium has a charge of \(2+\).
• Nitrogen has a charge of \(3-\).

The least common multiple of the absolute values of these charges (2 and 3) is 6. To balance, you need three barium ions (each with a 2+ charge) and two nitrogen ions (each with a 3- charge) to equalize at +6 and -6, respectively. This results in the neutral compound \(\text{Ba}_3\text{N}_2\).
Balancing accurately is key to predicting compound formation and stability, highlighting the importance of understanding these charges and their role.