The Major Laws of Chemistry

Energy is neither created nor destroyed.
Energy is neither created nor destroyed. Mmdi, Getty Images

Navigating the world of chemistry is much easier once you've got an understanding of the field's basic laws. The most important ones, briefly summarized below, describe the foundational concepts and principles of chemistry.

Avogadro's Law
Equal volumes of gases under identical temperature and pressure conditions will contain equal numbers of particles (atoms, ions, molecules, electrons, etc.).

Boyle's Law
At a constant temperature, the volume of a confined gas is inversely proportional to the pressure to which the gas is subjected:

PV = k

Charles' Law
At a constant pressure, the volume of a confined gas is directly proportional to the absolute temperature in Kelvin:

V = kT

Combining Volumes
Refer to Gay-Lussac's Law.

Conservation of Energy
Energy can be neither created nor destroyed; the energy of the universe is constant. This is the First Law of Thermodynamics.

Conservation of Mass
Matter can be neither created nor destroyed, though it can be rearranged. Mass remains constant in an ordinary chemical change. This principle is also known as conservation of matter.

Dalton's Law
The pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases.

Definite Composition
A compound is composed of two or more elements chemically combined in a defined ratio by weight.

Dulong–Petit Law
Most metals require 6.2 calories of heat in order to raise the temperature of one gram-atomic mass of metal by one degree Celsius.

Faraday's Law
The weight of any element liberated during electrolysis is proportional to the quantity of electricity passing through the cell and also to the equivalent weight of the element.

First Law of Thermodynamics
The total energy of the universe is constant and can be neither created nor destroyed.

This law is also known as conservation of energy.

Gay-Lussac's Law
The ratio between the combining volumes of gases and the product (if gaseous) can be expressed in small whole numbers.

Graham's Law
The rate of diffusion or effusion of a gas is inversely proportional to the square root of its molecular mass.

Henry's Law
The solubility of a gas (unless it is highly soluble) is directly proportional to the pressure applied to the gas.

Ideal Gas Law
The state of an ideal gas is determined by its pressure, volume, and temperature according to the equation:

PV = nRT

where P is the absolute pressure, V is the volume of the vessel, n is the number of moles of gas, R is the ideal gas constant, and T is the absolute temperature in Kelvin.

Multiple Proportions
When elements combine, they do so in the ratio of small whole numbers. The mass of one element combines with the fixed mass of another element according to certain ratios.

Periodic Law
The chemical properties of the elements vary periodically according to their atomic numbers.

Second Law of Thermodynamics
Entropy increases over time. Another way of stating this law is to say that heat cannot flow, on its own, from an area of cold to an area of hot.