Evidence of Chemical Change Physical and Chemical Changes

Objectives: Learn that a chemical changes involves the formation of a new substance Differentiate between chemical and physical changes

How can changes in matter be described? Matter is described by characteristic properties, either chemical or physical, unique to a particular substance

Physical properties Can be observed using your five senses Smell Color Texture Density Conductivity Physical state

Chemical properties The characteristic of a substance that describes its ability to change into other substances Chemical changes happen during chemical reactions

Physical Changes Any change that alters the appearance of a substance but does not change it into another substance Bending Crushing Cutting Melting Freezing boiling

Chemical Change Atoms are rearranged to form new substances with different properties Chemical reactions involve changes in properties and changes in energy that you can often observe

Evidences of chemical change Color change Gas bubbles form Light given off Temperature change Precipitate forms Odor change

Precipitate A solid that forms from liquids during a chemical reaction Solution – is a liquid where the solute is dissolved in the liquid

Changes in energy Endothermic reaction – more energy is required to break the bonds than reform – feels cold Exothermic reaction – less energy is required to break the bonds than reform them – feels hot