Chapter 2 notes: Matter PEPS Rainier Jr/Sr High School Mr. Taylor

Classifying Matter Matter is anything that has mass and takes up space. ▫Chemistry is the study of matter and how it interacts with other matter. Matter can exist as ▫An element, ▫A compound, or ▫A mixture.

Classifying Matter An element is a substance that cannot be broken down into simpler substances by chemical means (it takes a nuclear reaction!) ▫Elements are made of individual atoms. ▫Atoms are the simplest particle of an element that retains all the properties of that element. ▫Elements are identified by chemical symbols

Classifying Matter Compounds are substances made up of two or more different elements chemically combined. ▫A compound has different chemical and physical properties than the elements from which it is made. ▫Compounds are represented by chemical formulas that indicate which elements are present and how much of each is present.

Classifying Matter A pure substance is matter that has a fixed composition and definite properties. ▫A single element or a single compound! A mixture is two or more pure substances combined physically ▫Mixtures can be separated physically.  How can you separate a mixture of sugar and water?

Classifying Matter Mixtures can be either heterogeneous or homogeneous. ▫“Hetero” means ‘different’: a heterogeneous mixture is not the same throughout. ▫“Homo” means ‘the same’: it has uniform composition throughout. ▫A bowl of corn flakes vs. a cup of tea

Properties of Matter Substances have physical and chemical properties. ▫Physical properties describe the substance and can be observed without changing the substance. ▫Chemical properties describe how the substance interacts with other pure substances.

Properties of Matter Physical properties ▫Can be observed or measured  Color, shape, texture, density, boiling and melting points, and many others. ▫Density is a physical property.  Density is constant for a pure substance  Density = mass ÷ volume  Density determines buoyancy; less dense things “float” upward in more dense things.

Properties of Matter Chemical properties describe how substances respond to other pure substances ▫Flammability, reactivity, ionization potential, valence, and many more.

Changes of Matter Substances can undergo physical or chemical changes. ▫When a physical change has occurred you still have the same substance; it just has a new color, shape, texture, etc.  Melting, cutting, dissolving, and more. ▫When a chemical change has occurred you have a new substance(s) formed.  The new substance has new physical and chemical properties.  Burning, decomposition, cooking, and more.

That’s all for today!