Aim: How are physical and chemical changes different? Do Now: 1.Take out a calculator and reference tables. 2.What is the difference between an element, compound, and mixture?

What do drawings of elements, compounds, and mixtures look like?

How can we describe the properties of elements, compounds and mixtures? First – What is a property? Property is defined as a quality or characteristic of a thing. There are two types of properties discussed in chemistry – 1.Physical properties. 2.Chemical properties.

Physical Properties Can be observed without the production of new substances. Color, shape, phase, solubility (does it dissolve), density, melting point, boiling point, hardness, taste, weight, conductivity, malleability (does it bend), ductility (can it be made into a wire), mass, etc… A physical change is a change in the physical characteristics of the sample. Physical changes can be reversed.

Chemical Properties A chemical property is a substance’s ability to undergo a specific chemical change. Chemical properties can only be observed during a chemical change. During a chemical change, the composition of matter (its chemical formula) changes. These changes cannot be reversed by ordinary means. Chemical changes are also known as chemical reactions.

Parts of a Chemical Reaction Reactant – the substance that is present at the beginning of the reaction. Product – the substance produced as a result of the reaction. Example: Which are the reactants? Products? Baking powder + Vinegar  Water + Carbon Dioxide

Signs of a Chemical Change Things to look for include: The transfer of energy (heat or light has been released or absorbed). A change in color. The production of a gas. The formation of a precipitate (a solid that forms and settles out of a liquid mixture).

A Demonstration Are the changes physical or chemical? How do you know?

Activity/Homework #