Question

an ionic compound is named iron (ii) bromide. 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? table with columns: element (iron (ii), bromine), charge of one ion, total charge of ion(s) in compound, number of ion(s) in compound*

Explanation:

Step1: Determine ion charges

Iron (II) has a charge of $+2$ (since Roman numeral II indicates +2). Bromide ion (from bromine) has a charge of $-1$ (as bromine is in group 17, gains 1 electron).

Step2: Balance total charge

Let the number of $\text{Fe}^{2+}$ be $x$ and $\text{Br}^-$ be $y$. Total positive charge: $2x$, total negative charge: $y$. For neutral compound, $2x = y$. The smallest integers: $x = 1$, $y = 2$.

Step3: Write formula

The formula is $\text{FeBr}_2$ (1 $\text{Fe}^{2+}$ and 2 $\text{Br}^-$ ions).

Filling the table:

• Iron (II): Charge of one ion: $+2$; Total charge of ions: $+2$ (1 ion, $1\times(+2)$); Number of ions: $1$.
• Bromine: Charge of one ion: $-1$; Total charge of ions: $-2$ (2 ions, $2\times(-1)$); Number of ions: $2$.

Answer:

• Iron (II) Charge: $+2$, Total Charge: $+2$, Number of Ions: $1$
• Bromine Charge: $-1$, Total Charge: $-2$, Number of Ions: $2$
• Formula: $\boldsymbol{\text{FeBr}_2}$