Key Points

In a chemical equation, the reactants are written on the left, and the products are written on the right.

The coefficients next to the symbols of entities indicate the number of moles of a substance produced or used in the chemical reaction.

Understanding Chemical Formulas
Chemical formulas are symbolic representations of chemical compounds. They indicate the elements present in a compound and the ratio of these elements. Here are the essential components for writing chemical formulas:
1. Identify the Elements
- Determine which elements are involved in the compound.
- Use the periodic table to find the chemical symbols (e.g., H for hydrogen, O for oxygen).
2. Determine the Ratio of Elements
- Analyze how many atoms of each element are present.
- The ratio can be derived from the compound's molecular structure or empirical data.
3. Use Subscripts for Quantities
- If there is more than one atom of a particular element, write the number as a subscript immediately following the element's symbol (e.g., H₂O indicates 2 hydrogen atoms and 1 oxygen atom).
4. Combine the Elements
- Write the symbols of the elements in the order specified by chemical conventions (typically metal first, followed by nonmetals).
- For polyatomic ions (groups of atoms acting as a unit), use parentheses if needed (e.g., Ca(NO₃)₂).
5. Check for Charges (for Ionic Compounds)
- Ensure that the overall charge of the compound is neutral.
- Adjust the subscripts to balance the charges if necessary.
6. Use Proper Formatting
- Ensure the formula is clearly formatted with correct subscripts and parentheses to avoid confusion.
By following these guidelines, you can effectively write accurate chemical formulas for a variety of compounds. Understanding the structure and composition of compounds is crucial in chemistry.