Question

Write the chemical formulas for the following compounds: (a) aluminum hydroxide, (b) potassium sulfate, (c) copper(I) oxide, (d) zinc nitrate, (e) mercury(II) bromide, (f) iron(III) carbonate, \((\mathrm{g})\) sodium hypobromite.

Short answer

The chemical formulas for the given compounds are: (a) \(\text{Al(OH)}_{3}\), (b) \(\text{K}_{2}\text{SO}_{4}\), (c) \(\text{Cu}_{2}\text{O}\), (d) \(\text{Zn(NO}_{3}\text{)}_{2}\), (e) \(\text{HgBr}_{2}\), (f) \(\text{Fe}_{2}(\text{CO}_{3})_{3}\), and (g) \(\text{NaBrO}\).

Step-by-step solution

Identify elements and their charges

Aluminum (Al) has a charge of +3. Hydroxide (OH) has a charge of -1.

Combine elements

To balance the charges, we need 3 hydroxide groups for each aluminum atom. Therefore, the chemical formula is \(\text{Al(OH)}_{3}\). #b) Potassium sulfate#

Identify elements and their charges

Potassium (K) has a charge of +1. Sulfate (SO₄) has a charge of -2.

Combine elements

To balance the charges, we need 2 potassium atoms for each sulfate group. Therefore, the chemical formula is \(\text{K}_{2}\text{SO}_{4}\). #c) Copper(I) oxide#

Identify elements and their charges

Copper (Cu) has a charge of +1 (denoted by I). Oxygen (O) has a charge of -2.

Combine elements

To balance the charges, we need 2 copper atoms for each oxygen atom. Therefore, the chemical formula is \(\text{Cu}_{2}\text{O}\). #d) Zinc nitrate#

Identify elements and their charges

Zinc (Zn) has a charge of +2. Nitrate (NO₃) has a charge of -1.

Combine elements

To balance the charges, we need 2 nitrate groups for each zinc atom. Therefore, the chemical formula is \(\text{Zn(NO}_{3}\text{)}_{2}\). #e) Mercury(II) bromide#

Identify elements and their charges

Mercury (Hg) has a charge of +2 (denoted by II). Bromine (Br) has a charge of -1.

Combine elements

To balance the charges, we need 2 bromine atoms for each mercury atom. Therefore, the chemical formula is \(\text{HgBr}_{2}\). #f) Iron(III) carbonate#

Identify elements and their charges

Iron (Fe) has a charge of +3 (denoted by III). Carbonate (CO₃) has a charge of -2.

Combine elements

To balance the charges, we need 2 iron atoms for each 3 carbonate groups. Therefore, the chemical formula is \(\text{Fe}_{2}(\text{CO}_{3})_{3}\). #(g) Sodium hypobromite#

Identify elements and their charges

Sodium (Na) has a charge of +1. Hypobromite (BrO) has a charge of -1.

Combine elements

To balance the charges, we need 1 sodium atom for each hypobromite group. Therefore, the chemical formula is \(\text{NaBrO}\).

Key concepts

Ionic Compounds

Ionic compounds are formed when metals and non-metals chemically bond together. Metals, typically from the left side of the periodic table, lose electrons and become positively charged ions. Non-metals, often from the right side, gain these electrons and become negatively charged ions. The attraction between positively charged cations and negatively charged anions leads to the formation of an ionic bond.

When writing chemical formulas for ionic compounds, it is important to identify the ions involved and their respective charges. This is because the overall charge of an ionic compound should be neutral. For example, in aluminum hydroxide, aluminum ( Al ) has a charge of +3, while hydroxide ( OH ) has a charge of -1. To balance these charges, three hydroxide ions are required to balance one aluminum ion, forming the compound Al(OH) ₃.

Key characteristics of ionic compounds include high melting and boiling points, as well as the ability to conduct electricity when dissolved in water or melted. This conductivity is due to the free movement of ions in solution.

Charge Balancing

Charge balancing is an essential step in determining the chemical formula of an ionic compound. The goal is to ensure the total positive charge from the cations equals the total negative charge from the anions, achieving a neutral overall charge.

To balance charges, consider the charges of each ion involved in the compound. For instance, potassium ( K ) has a charge of +1, while the sulfate ion ( SO ₄) has a charge of -2. In order to balance these charges, two potassium ions are needed for each sulfate ion, resulting in the chemical formula K ₂ SO ₄.

There are some simple steps to follow:

• Identify the charge of each ion involved.
• Determine the ratio of ions needed to achieve charge neutrality.
• Write the chemical formula using the appropriate subscripts to indicate the number of each ion.

This method ensures that the resulting formula accurately represents a compound with no overall charge.

Polyatomic Ions

Polyatomic ions are ions composed of two or more atoms that are covalently bonded and have an overall charge. These ions can act as a single unit when participating in ionic bonding. Examples of common polyatomic ions include nitrate ( NO ₃⁻), sulfate ( SO ₄²⁻), and carbonate ( CO ₃²⁻).

Writing chemical formulas with polyatomic ions follows the same charge balancing principles as for single-atom ions. For instance, when forming zinc nitrate, zinc ( Zn ) has a charge of +2, while the nitrate ion has a charge of -1. To achieve charge balance, two nitrate ions are needed to balance one zinc ion, resulting in the formula Zn(NO₃)₂.

When writing formulas involving polyatomic ions, brackets are often used if more than one polyatomic ion is required to balance the charge. These brackets indicate that the polyatomic ion acts as one entity in the compound, and the subscript outside the bracket indicates the number of ions needed to balance the charge.