Lecture Notes for Feb 8, 2010

Chapter 3 : Matter and Energy What is matter ? Matter is defined as anything that occupies space and has mass. States of Matter: Solid: definite volume , definite shape Liquid: definite volume , takes the shape of the container Gas: expands to fill the volume and take the shape of the container Classification of Matter: -either a pure substance, which has constant composition. either elements or compounds -or a mixture, which has variable composition. heterogeneous or homogeneous ~Elements: substances which cannot be broken down into simpler substances by chemical reactions ~Compounds: chemical combinations of two or more elements (can be broken down into elements by chemical means) ~Homogeneous: uniform throughout. a solution. ex: sugar dissolved into water ~Heterogeneous: nonuniform throughout. ex: sand in a pail of water. Atoms and Molecules Smallest piece of an element is called an atom. >there are subatomic particles, but these are no longer the element Smallest piece of a compund is called a molecule >molecules are made of atoms >all molecules of a compound are identical >each molecule has the same number and the same type of atoms Properties of Matter -Physical properties are characteristics of matter that do not involve a change in the sample's chemical makeup . >characteristics that are directly observable. >ex: boiling point, melting point, density, color, and odor Changes in Matter -Chemical Changes involve a change int he properties of matter that change its composition >a chemical reaction >ex: rusting is iron combining with oxygen to make iron(III) oxide >ex: burning butane from a lighter changes it into carbon dioxide and water >silver combines with sulfur in the air to make tarnish