Properties of Matter
Physical Properties
A crystal of the mineral calcite has certain characteristic forms involving the angles between crystal faces. These forms are independent of the size of the crystal. The same crystals have specific cleavage planes along which they are easily broken, resulting in characteristic forms. The crystals have a density charateristic of calcite and a hardness. Properties such as color, transparency, surface appearance are physical properties. Taste, odor, and feel are physical properties of a substance. Many substances can go into solution with no chemicalchange so that solubility in various solvents is a physical characteristic or property. Electrical and thermal conductivity are physical propeties.
A physical change is one that alters the state or condition of matter. The chemical composition remains unaltered. Procesess such as cutting, breaking, machining, melting of solids are examples of physicalchanges. Water molecules are uneffected by the melting of ice.
Chemical Properties
The ways in which a substance undergoes chemical reactions are chemical properties. Substances are converted into other substances in the process of chemical reactions. A mixture of hydrogen andoxygen will explode on heating to form water. Water is a different substance than either hydrogen or oxygen. Water has very different physical properties than hydrogen or oxygen.The tendency to combine to form water is a chemical property of both hydrogen and oxygen. In a similar manner sodium metal and chlorine gas will combine to form table salt. This is a chemical change and results in a single substance with very different chemical and physical properties than the initial reactants. Chemical changes often release energy in the form of heat of light in the process. The burning of wood involves chemical changes and produces water and carbon dioxide.