Chemistry is the study of Matter and the transformation It can undergo. Matter is anything that Occupies space. It is the stuff that makes up All things. An element is a substance that cannot Be separated or broken down into Simpler substances by chemical means An atom is the smallest unit of an element That maintains the properties of That element. A compound is a substance made from Atoms of two or more different Elements that are chemically combined. A molecule is the smallest unit of a Substance that keeps all of the Physical and chemical properties Of that substance. A pure substance is a sample of matter, Either a single element or a Single compound, that has definite Chemical and physical properties. A mixture is a combination of two or More substances that are NOT Chemically combined. A mixture where everything is evenly Distributed is called homogeneous. A mixture that is NOT evenly distributed Is called a heterogeneous mixture. A chemical formula is a combination Of chemical symbols and numbers To represent a substance. Some properties of matter, such as Color and shape, are called Physical properties. Some physical properties are: Mass, volume and Density. An easily observed physical property Is its state: solid, liquid or gas. Melting point is the temperature and Pressure at which a solid Becomes a liquid. Boiling point is the temperature And pressure at which a liquid Becomes a gas. Solids, liquids and gases are matter, so they all have density. Density is a property of material independent of quantity or shape. 10.1 Density The units used for density depend on whether the substance is solid or liquid. For liquids use units of grams per milliliter (g/mL) For solids use density in units of g/cm3 or kg/m3. 10.1 Determining Density To find the density of a material, you need to know the mass and volume of a solid sample of the material. 1. Mass is measured with a balance or scale. 2. Use the displacement method or calculate the volume. Solving Problems A solid wax candle has a volume of 1,700 mL. The candle has a mass of 1,500 g. What is the density of the candle? Solution: § 1,500 g ÷ 1,700 mL = 0.8823529 g/mL Chemical property is a property of Matter that describes a substance’s Ability to participate is chemical reactions. Reactivity is the ability of a substance To combine chemically with Another substance. Flammability is the ability of a Substance to react in the presence Of oxygen and burn when Exposed to a flame. There are 2 kinds of changes for matter Chemical & Physical A physical change is any change in the size, shape, or phase of matter in which the identity of a substance does not change. For example, when water is frozen, it changes from a liquid to a solid. Any change that transforms one substance into a different substance is called a chemical change. Iron reacts with oxygen to form iron oxide. Ex. If you leave a nail outside, it rusts.