Topic 2: Changes in Matter Changes in matter can be classified two ways: Physical Change The substance changes form/state, but no new substances are formed. e.g. liquid to solid, solid to liquid, liquid to gas etc. 2. Chemical Change One or more new substances are formed. The reaction is difficult if not impossible to reverse. e.g acid dissolving metal to produce a gas, wood burning to produce smoke and ash.

Rules to determining if a change is chemical or physical: Heat is produced/absorbed. Starting material/chemicals is used up. Colour change Material/chemical with new properties is formed. Gas bubbles form in a liquid. A precipitate, (solid particles), form in a liquid. The change is difficult/impossible to reverse. *** If two or more of the above are observed the change is likely chemical. *** Physical Properties Any property that can be observed or measured without a new substance being formed. Examples: appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, etc.

Physical Properties Any property that can be observed or measured without a new substance being formed. Examples: appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, etc. They are classified as qualitative and quantitative. Qualitative: is a property that can be described not measured with numbers. (Colour) Quantitative: is a property that must be measured with numbers. (Melting point)

Chemical Properties Properties that describe how a substance reacts with another substance when forming a new substance. Examples: reacts with water, reacts with oxygen, reacts with pure substance, stability, combustibility, etc. http://www.youtube.com/watch?v=-Ypwtjp0FSE