Describing Matter Section 1

Points to Cover Give Examples of matter’s different properties Describe how density is used to identify different substances Compare physical and chemical properties Explain what happens to matter during physical and chemical changes

Physical Property Any property that can be observed or measured without changing the identity of the matter Examples: Color, Odor Volume

More Physical Properties Thermal Conductivity State Malleability Ductility Solubility Density

Density The amount of matter in a given space D=M/V Density is expressed in g/cm3 and g/mL

Density Density is useful in identifying a substance because of two reasons (1) it is the same at a given temp and pressure (2) density is usually different for all substances

Chemical Properties Chemical properties describe a substance based on its ability to change into a new substance with different properties Examples: Flammability, Reactivity

Chemical Vs. Physical Properties Characteristic properties of a substance are always the same whether the sample you’re observing is large or small

Physical Changes A change that affects one or more physical properties of a substance Example: water vapor condensing from a gas to a liquid. It’s state and density change.

Physical Changes Most physical changes can be undone Example: Ice melts to form water, however you can freeze that water again to form ice

Chemical Changes Occurs when one or more substances are change into entirely new substances with different properties The new substance will have a new chemical composition. Example: Burning a piece of wood, milk souring

Chemical Changes Since a new substance is formed, a chemical change cannot be undone unless another chemical change occurs.

Review