Topics > Matter & Measurements > Units

Units provide a standardized framework to express quantities and ensure that measurements are consistent, comparable, and easily understood.

Various types of units are used to represent different types of quantities. Some commonly used units include:

• SI Units: The International System of Units (SI) is the most widely used system of measurement in science, including chemistry. It provides a standardized set of units for fundamental quantities such as length (meter, m), mass (kilogram, kg), time (second, s), temperature (kelvin, K), amount of substance (mole, mol), and more.

• Derived Units: Derived units are formed by combining base units. For example, volume is derived from the base unit of length, resulting in units such as cubic meter (m³) or liter (L). Other derived units in chemistry include molar concentration (mol/L or M), velocity (m/s), energy (joule, J), and pressure (pascal, Pa), among others.

• Metric Prefixes: Metric prefixes are used to indicate decimal multiples or submultiples of a unit. For example, kilo- (k) represents a factor of 1000, so 1 kilogram (kg) is equal to 1000 grams (g). Similarly, milli- (m) represents a factor of 0.001, so 1 milliliter (mL) is equal to 0.001 liters (L).