Problem 22 - Chemistry Matter and Change

Question

Write formulas for the ionic compounds formed by the following ions. cesium and nitride

Step-by-Step Solution

Answer

The formula for the ionic compound is \( \text{Cs}_3\text{N} \).

Step 1: Identify the Ions

First, we need to determine the charges of the ions involved. Cesium typically forms a cation with a charge of +1, written as \( \text{Cs}^+ \). Nitride is an anion with a charge of -3, written as \( \text{N}^{3-} \).

Step 2: Determine the Ratio of Ions

To form a neutral ionic compound, the total positive charge must balance the total negative charge. Since cesium has a charge of +1 and nitride has a charge of -3, we need three cesium ions to balance one nitride ion. Thus, the ratio is 3:1.

Step 3: Write the Chemical Formula

The chemical formula for the ionic compound is determined by writing the symbol for the cation followed by the symbol for the anion, each with subscripts indicating the number needed to balance the charges. Therefore, the formula will be \( \text{Cs}_3\text{N} \).

Key Concepts

Chemical Formula

A chemical formula is a crucial element in understanding ionic compounds. It represents the simplest ratio of the ions involved in the compound, showing how elements combine based on their charges.
The formula not only indicates the types of ions present but also displays the proportion needed to maintain electrical neutrality. For example, in the compound formed by cesium and nitride, the formula is \( \text{Cs}_3\text{N} \). This chemical formula reveals that three cesium ions (\( \text{Cs}^+ \)) balance the charge of one nitride ion (\( \text{N}^{3-} \)).

• Subscripts in a chemical formula show the number of ions needed for charge balance.
• The chemical formula must reflect a balanced compound, always electrically neutral.

Cation and Anion Charges

Understanding cation and anion charges is essential to writing chemical formulas. Cations are positively charged ions, whereas anions carry a negative charge. The charge depends on how many electrons are lost or gained by an atom.

• Cesium (Cs): Often forms a cation with a +1 charge. This is because cesium tends to lose one electron to achieve a stable electron configuration.
• Nitride (N): Forms an anion with a -3 charge, as nitrogen gains three electrons to fill its valence shell for stability.

Knowing the charges allows us to determine the proper ionic pairings needed for charge balance in compounds.

Charge Balance

Charge balance is a critical principle in forming ionic compounds. This concept is based on the need to have a neutral compound, with the total positive and negative charges canceling each other out. If the charges do not balance, the compound is not stable.
When cesium and nitride ions come together, the charge balance concept dictates that:

• The positive ions (cesium, \( \text{Cs}^+ \)) must equal in number and magnitude the negative ions (nitride, \( \text{N}^{3-} \)).
• Three cesium ions are required to balance out the charge of one nitride ion, achieving an overall neutral charge.

The correct formulation, \( \text{Cs}_3\text{N} \), showcases how charge balance is maintained to form a stable ionic compound.

Cesium

Cesium is a fascinating element primarily known for forming cations with a +1 charge. This alkali metal, found in Group 1 of the periodic table, is highly reactive and has a single electron in its outer shell.
Cesium readily loses this electron, making it a perfect candidate for forming ionic bonds.

• Being a soft, gold-colored metal, cesium reacts vigorously, often used in atomic clocks due to its precise frequency standard.
• Its propensity to lose one electron results in the consistent formation of \( \text{Cs}^+ \) ions seen in ionic compounds.

This property contributes significantly to cesium's ability to combine with anions such as nitride to form stable compounds.

Nitride

Nitride is the term used for anions that nitrogen forms when gaining electrons. The nitride ion (\( \text{N}^{3-} \)) attains a stable electron configuration by adding three electrons to its valence shell.
This gives it a full outer shell, replicating the electron arrangement of neon, a noble gas.

• Nitrogen, often found in the form of nitride, plays an essential role in forming diverse and stable ionic compounds.
• The \( \text{N}^{3-} \) ion characteristically pairs with positive ions, like cesium, to create compounds with neutral charges.

Understanding nitride is fundamental in apprehending how ionic compounds like \( \text{Cs}_3\text{N} \) are created, balancing both electrical charge and electron configurations.