Writing Chemical Formulas
Rules for Writing Chemical Formulas
Identify the symbols of elements.
Determine the valency of each element.
Cross-multiply the valencies to balance the formula.
Valency and Examples
Valency is the combining capacity of an element.
Valency Table of Common Elements
| Element | Symbol | Valency |
|---|---|---|
| Hydrogen | H | 1 |
| Oxygen | O | 2 |
| Nitrogen | N | 3 |
| Carbon | C | 4 |
| Sodium | Na | 1 |
| Chlorine | Cl | 1 |
Examples of Chemical Formulas:
Water (H₂O) → H (1) and O (2) → H₂O
Ammonia (NH₃) → N (3) and H (1) → NH₃
Calcium Chloride (CaCl₂) → Ca (2) and Cl (1) → CaCl₂
(Diagram: Valency table and chemical formula examples)