Science, Tech, Math › Science The Major Laws of Chemistry Understanding these basic principles makes navigating chemistry easier Share Flipboard Email Print Anawat Sudchanham / EyeEm / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated November 07, 2019 Navigating the world of chemistry is much easier once you have an understanding of the field's basic laws. Here are brief summaries of the most important laws, the foundational concepts, and principles of chemistry: Avogadro's LawEqual volumes of gases under identical temperature and pressure will contain equal numbers of particles (atoms, ions, molecules, electrons, etc.). Boyle's LawAt a constant temperature, the volume of a confined gas is inversely proportional to the pressure to which the gas is subjected: PV = k Charles' LawAt a constant pressure, the volume of a confined gas is directly proportional to the absolute temperature in Kelvin: V = kT Combining VolumesRefer to Gay-Lussac's Law. Conservation of EnergyEnergy can neither be created nor destroyed; the energy of the universe is constant. This is the First Law of Thermodynamics. Conservation of MassMatter can neither be 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 LawThe pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases. Definite CompositionA compound is composed of two or more elements chemically combined in a defined ratio by weight. Dulong-Petit LawMost metals require 6.2 calories of heat to raise the temperature of one gram-atomic mass of metal by one degree Celsius. Faraday's LawThe 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 ThermodynamicsThe total energy of the universe is constant and can neither be created nor destroyed. This law is also known as Conservation of Energy. Gay-Lussac's LawThe ratio between the combining volumes of gases and the product (if gaseous) can be expressed in small whole numbers. Graham's LawThe rate of diffusion or effusion of a gas is inversely proportional to the square root of its molecular mass. Henry's LawThe solubility of a gas (unless it is highly soluble) is directly proportional to the pressure applied to the gas. Ideal Gas LawThe 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 ProportionsWhen 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 LawThe chemical properties of the elements vary periodically according to their atomic numbers. Second Law of ThermodynamicsEntropy 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.