What does a subscript in a chemical formula tell you
The Correct Answer and Explanation is:
A subscript in a chemical formula indicates the number of atoms of a particular element in one molecule or formula unit of a compound. It is a small number written just below and to the right of the element symbol. The presence of subscripts helps in understanding the composition and structure of the substance. If there is no subscript, it means there is exactly one atom of that element in the formula.
For example, in the formula for water, H₂O, the subscript “2” tells us that there are two hydrogen atoms and one oxygen atom in each molecule of water. Similarly, in carbon dioxide (CO₂), the subscript “2” tells us that each molecule contains two oxygen atoms.
In ionic compounds, subscripts also help in balancing the charges of the ions. For example, in sodium chloride (NaCl), there is one sodium ion (Na⁺) for every chloride ion (Cl⁻), so no subscript is needed. But in calcium chloride (CaCl₂), the subscript “2” indicates that two chloride ions are needed to balance the two positive charges of the calcium ion (Ca²⁺).
If a molecule consists of multiple polyatomic ions, subscripts are used to indicate the number of each ion present. For example, in aluminum sulfate (Al₂(SO₄)₃), the subscript “2” next to Al indicates two aluminum ions, and the subscript “3” next to SO₄ indicates three sulfate ions in the compound.
Subscripts are crucial for understanding the stoichiometry of chemical reactions, the proportions of elements in a compound, and the behavior of substances in various chemical processes. They are foundational to the language of chemistry, ensuring that the correct quantities of elements and ions are represented.
