Question

an ionic compound is named chromium (ii) oxide. complete the table to determine the number of ions of each element in one formula unit of the compound. enter a negative sign before negative numbers. positive numbers do not need a positive sign. in one formula unit what is the formula for the ionic compound? element chromium (ii) oxygen charge of one ion yellow box yellow box total charge of ion(s) in compound yellow box yellow box number of ion(s) in compound* yellow box yellow box

Explanation:

Step1: Determine ion charges

Chromium (II) has a charge of \( +2 \) (since it's chromium (II)). Oxygen (oxide ion) has a charge of \( -2 \).

Step2: Balance charges

To balance the charges, the number of chromium (II) ions and oxide ions should be such that the total positive charge equals the total negative charge. Let the number of \( \text{Cr}^{2+} \) be \( x \) and \( \text{O}^{2-} \) be \( y \). Then \( 2x = 2y \), so \( x = y = 1 \) (simplest ratio).

Step3: Write the formula

The formula is \( \text{CrO} \) (since one \( \text{Cr}^{2+} \) and one \( \text{O}^{2-} \) balance the charges).

For the table:

• Chromium (II) ion charge: \( +2 \)
• Oxygen ion charge: \( -2 \)
• Total charge of chromium (II) ions in compound: \( +2 \) (1 ion × \( +2 \))
• Total charge of oxygen ions in compound: \( -2 \) (1 ion × \( -2 \))
• Number of chromium (II) ions: 1
• Number of oxygen ions: 1

Answer:

The formula for chromium (II) oxide is \( \text{CrO} \).
Table filled:

• Chromium (II) charge: \( +2 \), total charge: \( +2 \), number of ions: 1
• Oxygen charge: \( -2 \), total charge: \( -2 \), number of ions: 1