|Themes > Science > Chemistry > General Chemistry > Matter > Atoms, Ions, and Molecules > Structural Formula|
Structural formulas show every atom and every bond, as well as the unshared electron pairs found in a molecule. Atoms are represented by their atomic symbol. Bonds are represented by solid black lines. A single black line or dash represents 2 shared electrons in a single covalent bond. Two black lines represent 4 shared electrons in a double covalent bond. Three black lines represent 6 shared electrons in a triple covalent bond. An unshared electron pair is represented by two dots paired together adjacent to the atomic symbol.
In the following examples, including structural formulas of water (H2O), ammonia (NH3), and sulfuric acid (H2SO4), unshared electron pairs are represented by red dots.
Structural formula of Water - H2O
Structural formula of Ammonia - NH3