Matter is anything that has mass and takes up space. Chemistry is the study of matter's properties and how it changes. Matter has physical properties, which can be observed without changing its substance, and chemical properties, which describe its ability to change into different substances through chemical reactions. Elements are pure substances that cannot be broken down further, while compounds are made of two or more elements chemically bonded together. Mixtures contain two or more substances mixed together without chemical bonding. Mixtures can be either heterogeneous, where the parts are visible, or homogeneous, where the parts are evenly mixed together.