Question

Give the formula and name for each ionic compound formed between the two listed ions. a) \(\mathrm{NH}_{4}^{+}\) and \(\mathrm{N}^{3-}\) b) \(\mathrm{Mg}^{2+}\) and \(\mathrm{CO}_{3}^{2-}\) c) \(\mathrm{Al}^{3+}\) and \(\mathrm{OH}^{-}\)

Short answer

a) \((NH_4)_3N\), Ammonium Nitride; b) \(MgCO_3\), Magnesium Carbonate; c) \(Al(OH)_3\), Aluminum Hydroxide.

Step-by-step solution

Identify the Ions and Their Charges

We need to first identify the charges of the given ions. In a): \(\mathrm{NH}_{4}^{+}\) has a charge of \(+1\) and \(\mathrm{N}^{3-}\) has a charge of \(-3\). In b): \(\mathrm{Mg}^{2+}\) has a charge of \(+2\) and \(\mathrm{CO}_{3}^{2-}\) has a charge of \(-2\). In c): \(\mathrm{Al}^{3+}\) has a charge of \(+3\) and \(\mathrm{OH}^{-}\) has a charge of \(-1\).

Determine the Chemical Formula

For each pair of ions, the chemical formula must be neutral, balancing the total positive and negative charges. - a) Combine \(\mathrm{NH}_{4}^{+}\) and \(\mathrm{N}^{3-}\) to form \(\mathrm{(NH}_{4})_{3}\mathrm{N}\).- b) Combine \(\mathrm{Mg}^{2+}\) and \(\mathrm{CO}_{3}^{2-}\) to form \(\mathrm{MgCO}_{3}\). - c) Combine \(\mathrm{Al}^{3+}\) and \(\mathrm{OH}^{-}\) to form \(\mathrm{Al(OH)}_{3}\).

Name the Compounds

Using the standard naming conventions for ionic compounds:- a) \(\mathrm{(NH}_{4})_{3}\mathrm{N}\) is named Ammonium Nitride.- b) \(\mathrm{MgCO}_{3}\) is named Magnesium Carbonate.- c) \(\mathrm{Al(OH)}_{3}\) is named Aluminum Hydroxide.

Key concepts

Chemical Formulas

Chemical formulas are representations of a compound, indicating the elements involved and the number of atoms of each element in the compound.
In ionic compounds, these formulas are crucial because they ensure that the total positive and negative charges balance to make the compound neutral. For example, when you have ions with charges - like \( \mathrm{NH}_{4}^{+} \) (ammonium) which has a charge of +1, and \( \mathrm{N}^{3-} \) (nitride) which has a charge of -3, - a proper chemical formula balances these charges. Therefore, the formula \( (\mathrm{NH}_{4})_{3}\mathrm{N} \) emerges, showing that three ammonium ions are needed for every single nitride ion to neutralize the charges.
This exemplifies how the formula portrays atomic count as well as balance in charge. When combining these ions, always ensure:

• The net charge is zero.
• An entire number ratio of ions where necessary is used.

Ion Charges

Ion charges, also known as oxidation states, are pivotal in understanding how ions combine to form compounds.
An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net positive or negative charge.
Understanding these charges is the foundation for predicting the formula of ionic compounds.Ions with the same charge magnitude but opposite signs can directly combine to form a neutral compound.
For example:

• \( \mathrm{Mg}^{2+} \) pairs with \( \mathrm{CO}_{3}^{2-} \) to form \( \mathrm{MgCO}_{3} \), as their charges of +2 and -2 cancel each other out.

For ions with different magnitudes, we use subscripts to indicate how many ions are needed to balance the charge.
For instance:

• \( \mathrm{Al}^{3+} \) and \( \mathrm{OH}^{-} \) combine to form \( \mathrm{Al(OH)}_{3} \), requiring three hydroxide ions per one aluminum ion to neutralize the charges.

When constructing a formula, ensure that the sum of the charges from all ions equals zero.
This ensures the compound is stable and neutral.

Compound Naming

Naming ionic compounds follows a systematic approach dictated by conventions that describe the elements and their types within the compound.
Firstly, the name of the cation (positive ion) commonly precedes the anion (negative ion). Consider the process:- When naming \( (\mathrm{NH}_{4})_{3}\mathrm{N} \), the \( \mathrm{NH}_{4}^{+} \) is an ammonium ion and \( \mathrm{N}^{3-} \) is a nitride ion, thus the compound is known as Ammonium Nitride.- For \( \mathrm{MgCO}_{3} \), where \( \mathrm{Mg}^{2+} \) is magnesium and \( \mathrm{CO}_{3}^{2-} \) is carbonate, the name becomes Magnesium Carbonate.It's important to know the following naming rules:

• Cations from a single element (like \( \mathrm{Mg}^{2+} \)) are named their elemental name.
• Anions are named with the suffix "-ide" if they derive from a single element (like \( \mathrm{N}^{3-} \) becomes Nitride).
• For polyatomic ions (like \( \mathrm{CO}_{3}^{2-} \)), unique names like "carbonate" are used.

Compound naming is a way to communicate information about the compound’s composition clearly through the use of systematic terminology.