Question

Complete the following table with the formula of the compound that forms between each pair of ions: $$\begin{array}{|lllll|}\hline & {\mathrm{NO}}_2^{-}& {\mathrm{CO}}_3^{2-}& {\mathrm{HSO}}_4^{-}& {\mathrm{PO}}_4^{3-}\\ {\mathrm{Li}}^{+}& & & & \\ {\mathrm{Cu}}^{2+}& & & & \\ {\mathrm{Ba}}^{2+}& & & & \\ \hline\end{array}$$

Short answer

LiNO${}_2$, Li${}_2$CO${}_3$, LiHSO${}_4$, Li${}_3$(PO${}_4$); Cu(NO${}_2$)${}_2$, CuCO${}_3$, Cu(HSO${}_4$)${}_2$, Cu${}_3$(PO${}_4$)${}_2$; Ba(NO${}_2$)${}_2$, BaCO${}_3$, Ba(HSO${}_4$)${}_2$, Ba${}_3$(PO${}_4$)${}_2$

Step-by-step solution

- Understanding the Problem

To complete the table, identify the simplest formula for the compound formed between each cation and anion pair.

- Combining Ions

Combine the ions to form neutral compounds. Use the charges on the ions to determine the ratio in which the ions combine.

- Formula for $\text{Li}\text{^}+$ and ${\text{NO}}_2\text{^}-$

The formula for the compound is ${\text{LiNO}}_2$.

- Formula for $\text{Li}\text{^}+$ and ${\text{CO}}_3\text{^}2-$

Two ${\text{Li}}^{+}$ ions are needed to balance the ${\text{CO}}_3^{2-}$ ion's charge. The formula is ${\text{Li}}_2{\text{CO}}_3$.

- Formula for $\text{Li}\text{^}+$ and ${\text{HSO}}_4\text{^}-$

The formula for the compound is ${\text{LiHSO}}_4$.

- Formula for $\text{Li}\text{^}+$ and ${\text{PO}}_4\text{^}3-$

Three ${\text{Li}}^{+}$ ions are needed to balance the ${\text{PO}}_4^{3-}$ ion's charge. The formula is ${\text{Li}}_3{\text{PO}}_4$.

- Formula for ${\text{Cu}}^{2+}$ and ${\text{NO}}_2^{-}$

Two ${\text{NO}}_2^{-}$ ions are needed to balance the ${\text{Cu}}^{2+}$ ion's charge. The formula is $\text{Cu}{\text{(NO}}_2{\text{)}}_2$.

- Formula for ${\text{Cu}}^{2+}$ and ${\text{CO}}_3^{2-}$

The formula for the compound is ${\text{CuCO}}_3$.

- Formula for ${\text{Cu}}^{2+}$ and ${\text{HSO}}_4^{-}$

Two ${\text{HSO}}_4^{-}$ ions are needed to balance the ${\text{Cu}}^{2+}$ ion's charge. The formula is $\text{Cu}{\text{(HSO}}_4{\text{)}}_2$.

- Formula for ${\text{Cu}}^{2+}$ and ${\text{PO}}_4^{3-}$

Use the lowest common multiple of the charges to get the ratio of ions. The formula is ${\text{Cu}}_3{\text{(PO}}_4{\text{)}}_2$.

- Formula for ${\text{Ba}}^{2+}$ and ${\text{NO}}_2^{-}$

Two ${\text{NO}}_2^{-}$ ions are needed to balance the ${\text{Ba}}^{2+}$ ion's charge. The formula is $\text{Ba}{\text{(NO}}_2{\text{)}}_2$.

- Formula for ${\text{Ba}}^{2+}$ and ${\text{CO}}_3^{2-}$

The formula for the compound is ${\text{BaCO}}_3$.

- Formula for ${\text{Ba}}^{2+}$ and ${\text{HSO}}_4^{-}$

Two ${\text{HSO}}_4^{-}$ ions are needed to balance the ${\text{Ba}}^{2+}$ ion's charge. The formula is $\text{Ba}{\text{(HSO}}_4{\text{)}}_2$.

- Formula for ${\text{Ba}}^{2+}$ and ${\text{PO}}_4^{3-}$

Use the lowest common multiple of the charges to get the ratio of ions. The formula is ${\text{Ba}}_3{\text{(PO}}_4{\text{)}}_2$.

Key concepts

Chemical Formulas

When you see terms like $L{i}_{2}C{O}_3$ or $Cu(N{O}_2{)}_2$, these are chemical formulas. A chemical formula tells you the types and numbers of atoms in a substance. It uses element symbols from the periodic table and subscript numbers to show how many atoms of each element are in a molecule. For example, $H_{2}O$ means there are two hydrogen atoms and one oxygen atom in a water molecule. Similarly, $C{O}_2$ tells us there is one carbon atom and two oxygen atoms in each carbon dioxide molecule. Understanding these formulas is essential to identify compounds and understand their composition. Breaking down chemical formulas makes it easier to study chemical reactions and properties.

Ionic Bonding

Ionic bonding is the force that holds atoms together in an ionic compound. This type of bond forms when atoms transfer electrons from one to another, creating ions. Metals lose electrons and become positively charged cations, while non-metals gain those electrons and become negatively charged anions. For example, when sodium (\text{Na}) reacts with chlorine (\text{Cl}), sodium loses an electron to become \text{Na}^+ and chlorine gains an electron to become \text{Cl}^-. The opposite charges attract, forming the ionic compound $NaCl$, which is table salt. These bonds are strong, and they create crystalline structures that usually dissolve in water and conduct electricity.

Cation and Anion Pairing

Creating ionic compounds involves careful pairing of cations and anions. The goal is to have a neutral compound, meaning the total positive charge from the cations equals the total negative charge from the anions. Let's break this down further:

• Cations are positively charged ions, typically formed from metals. Examples include \text{Li}^+ and \text{Cu}^{2+}.
• Anions are negatively charged ions, typically formed from non-metals. Examples include \text{NO}_2^{-} and \text{CO}_3^{2-}.

In an ionic compound like $L{i}_{2}C{O}_3$, two \text{Li}^+ cations pair with one \text{CO}_3^{2-} anion to balance the charges. In $Cu(N{O}_2{)}_2$, one \text{Cu}^{2+} cation pairs with two \text{NO}_2^{-} anions. Understanding how to pair these ions correctly is key to writing the correct chemical formulas.

Neutral Compounds

A crucial principle in ionic bonding is the formation of neutral compounds. This means the total charge of the compound must be zero. Every time you write the formula for an ionic compound, make sure the sum of the positive and negative charges equals zero. Here's how:

• Identify the charges of each ion.
• Determine how many of each ion are needed to balance the charges.
• Write the formula with the appropriate subscripts to show these quantities.

For example, let's look at $Ba(N{O}_2{)}_2$. Barium forms a \text{Ba}^{2+} ion, and nitrite forms a \text{NO}_2^{-} ion. You need two nitrite ions to balance one barium ion. The charges are +2 from barium and 2 x (-1) = -2 from two nitrite ions, resulting in a neutral compound. This balance ensures that the compound has no overall charge and is stable.