Matter is divided into elements, compounds and mixtures. Elements are the pure form of matter and contain only one type of atom. Compounds are formed when two or more elements chemically combine. In this process, each individual element loses its individual properties. Mixtures, on the other hand, are formed when two or more elements combine physically, yet all the individual elements retain their individual properties. Mixtures can be homogeneous or heterogeneous in nature. A homogeneous mixture has uniform concentration throughout, whereas a heterogeneous mixture has non-uniform concentration. Mixtures can be separated into individual components by making use of an individual component's properties. For example, salt in water (i.e. salt water) is a homogeneous mixture and can be separated back into salt and water by evaporation and condensation.