Most materials (like cement, for example, which contains sand, lime, water, and other substances) are not considered chemicals, but mixtures. Chemically pure substances, like sulfuric acid, H 2SO 4 have specific atom ratios (2 H : 1S : 4 O in this case). Materials are often complex mixtures which do not have atoms in definite ratios. These properties are easily defined and measured without reference to atoms.Ĭhemistry and Physics often complement each other in the development of new materials. In contrast to chemical properties, physical properties do not require explanations involving atoms or molecules Physical properties include the ductility, density, or hardness of the metal used to anchor the molecular motors. The mechanical work can then be measured and characterized by standard methods of physics. The molecule is bonded to a metal surface, so that the mechanical energy might be harnessed as shown here The action of these devices results from a change in shape of an azobenzene molecule (molecular shape and bonding tendencies are chemical properties) when it absorbs light. Chemistry explains or understands any subject in terms of the properties of atoms and molecules.Ĭhemistry provides a unique perspective that complements Physics in many areas of contemporary research.įor example, nanotechnology techniques have been applied to building “molecular motors”, artificial muscles, and molecular electronics. So chemistry is defined by its approach, not its subject matter. Chemists are unique because they understand or explain everything, even the subjects studied by physicists, in terms of the properties of just over 100 kinds of atoms found in all matter, and the amazing variety of molecules that are created by forming and breaking bonds between atoms. These are normally considered the subject of Physics. Matter is also composed of quarks, which transform by annihilation, of metals which transform by annealing, and of stars which may transform by supernovae. Chemistry isn't the only science that deals with the composition and transformations of matter. But this definition is too broad to be useful. \)Ĭhemistry has been defined as the science that is concerned with the composition, properties, and structure of matter and with the ways in which substances can change from one form to another.
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