This document provides an overview of chemistry unit 2 which covers how matter changes. It discusses the three common states of matter, physical and chemical properties, and how matter undergoes physical and chemical changes. It also addresses mixtures as combinations of substances and how mixtures can be separated. The document defines elements and compounds, and explains the organization of elements in the periodic table. It describes how all compounds obey the laws of definite and multiple proportions.
7. Physical Properties of Matter A physical property is a characteristic that can be observed or measured without changing the sample ’s composition.
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14. Chemical Changes A change that involves one or more substances turning into new substances is called a chemical change . Examples: Decomposing, rusting, exploding, burning, or oxidizing are all terms that describe chemical changes.
31. Percent by Mass The relative amounts are expressed as percent by mass , the ratio of the mass of each element to the total mass of the compound expressed as a percentage.
