Key Concepts: A chemical’s usefulness is determined by its chemical and physical properties Changes can be classified as chemical or physical We can classify pure substances by observing their properties. Ionic compounds are made up of positive and negative ions Molecular compounds are made up of distinct molecules Many consumer products are developed from petrochemicals Chapter 5: Chemicals and their Properties

5.1 Properties and Changes

physical property: a description of the appearance of a substance. It does not involve forming a new substance. Requires you to use your five senses to observe. e.g. colour, texture, density, odor, solubility, taste, melting point, and physical state, hardness, magnetism, luster, malleability. chemical property: a description of the changes a substance undergoes as it changes into one or more new substance(s) e.g. Reaction with an acid or base, flammability, bleaching ability, corrosion, rust, production of a gas, reactivity. Physical and Chemical Properties

physical changes: does not produce a new substance and can sometimes be easily reversed. e.g. changes of state (melting, evaporating, condensation, sublimation and dissolving). Dissolving sugar in water can be reversed by evaporating the water off Cutting a log in half cannot be reversed Physical and Chemical Changes

change a substance undergoes which produces one or more new substances. e.g. new colour appears, a solid or precipitate appears, heat/light is absorbed or produced, bubbles are formed, change is usually difficult to reverse. Forest fires, rusting of a vehicle, rotting of banana are impossible to reverse A rechargeable battery can be reversed Chemical Change:

Pg 178 #2-5,11 (read pg 175 to answer 11) Finish Lab Safety Booklet Get any sheets/lab booklet signed Finish chemistry title page for Friday Homework: