Elements An element is a substance that cannot be broken down into simpler substances. GoldAluminumCarbonIodine
Elements An atom is the smallest particle of an element. An element has a fixed composition because it contains only one type of atom.
Compounds A compound is a substance that is made from two or more elements and can be broken down into those elements. Silicon Oxygen Silicon dioxide
Mixtures A heterogeneous mixture is a mixture where the parts are noticeably different from one another.
Mixtures A homogeneous mixture is a mixture where you cannot tell the difference between the parts of the mixture.
Mixtures When substances dissolve and form a homogeneous mixture, that mixture is called a solution.
Mixtures A suspension is a heterogeneous mixture that separates into layers over time.
Mixtures A colloid contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension. Colloids do not separate into layers. You cannot use a filter to separate the parts of a colloid.
Physical Properties A physical property is any characteristic of a material that can be observed or measured without changing the composition of the substances in the material.
Physical Properties Conductivity is a material’s ability to allow heat or electricity to flow.
Physical Properties Melting point is the temperature at which a substance changes from a solid to a liquid.
Physical Properties Boiling point is the temperature at which a substance changes from a liquid to a gas
Using Properties to Separate Mixtures Filtration is a process that separates materials based on their size. Distillation is a process that separates liquids by their boiling points.
Physical Changes A physical change occurs when some of the properties of a material change, but the substances in the material stay the same.
Observing Chemical Properties A chemical property is any ability to produce a change in the composition of matter. Chemical properties can be observed only during a chemical change.
Observing Chemical Properties Reactivity describes the ability of a substance to chemically combine with other substances.
Observing Chemical Properties Flammability is a material’s ability to burn in the presence of oxygen.
Recognizing Chemical Changes A chemical change occurs when a substance reacts and forms one or more new substances.
Recognizing Chemical Changes Three common indicators of a chemical change are a change in color, the production of a gas, and the formation of a precipitate.
Is a Change Chemical or Physical When matter undergoes a chemical change, the composition of the matter changes. When matter undergoes a physical change, the composition of matter remains the same.