What MATTERS in Physical Science? Notes are in Yellow Revised

The Properties of Matter We know that matter is what makes up an object, but how do we describe this matter? If you know the properties of an object, then you may be able to identify it.

Physical Properties The Physical Property of matter can be observed or measured. For example, color, mass, volume, taste, smell, etc. You use physical properties all the time to make decisions (ex: what clothes to wear).

Physical Properties Physical properties can change, but the substance doesn’t change (i.e., salt water). You can separate the properties that make up the substance. How can you separate salt from water?

Density: A Physical Property You know the formula for density, which involves the volume divided into the mass: Mass M Density = Volume or D = V You can use density to identify a substance.

Using the Physical Property of Density There are two (2) ways that density can help identify an object: 1)The density of a particular substance is always the same at a given pressure and temperature. Ex: copper. Solid copper at 20 o C and normal atmospheric pressure will always have a density of 8.96 g/cm 3

Using the Physical Property of Density 2) The density of one substance is usually different than the density of another substance (when it is at the same temperature and atmospheric pressure).

The Physical Property of Density Fool’s Gold So, why is it important to know that density can be used to identify specific objects? The example learned the hard way: Pyrite (Fool’s Gold) What do you think happened when people found pyrite? How did they prove it was pyrite? Gold vs Pyrite

Displacement You know that you can find the volume of a solid (length x width x height, which is 3, and liquid, which is in mL, L). How do you get the volume of an irregular shaped object? Find the volume of a certain amount of water. Add the object to the water. Subtract the measurement of the water from the object and water together. Then, divide the volume into the mass.

Archimedes and the Volume of Gold Archimedes knew the density of gold (19.32 g/cm 3 ) King asked him to figure out if gold crown was real. What did Archimedes do with the crown to find the volume? How did he then find out if the crown was real gold?

Physical Change An actual physical change is an actual change of an object that only changes its appearance (measurement or what can be seen.) Changes in mass, volume, density, changes in state (boiling, freezing) are all examples of physical change.

Chemical Properties, Chemical Change Chemical Properties describe a substance based on its ability to change into a new substance with different properties. Example: ability to react; flammability Chemical Change: when a substance can change into another substance. Examples: burning, baking, digestion, photosynthesis, etc. You can’t undo chemical changes unless you have another chemical change.

Characteristics of Physical Change CHANGES IN STATE (SOLID, LIQUID, GAS) CHANGES IN SIZE AND/OR SHAPE CHANGES IN COLOR (NO CHEMICALS INVOLVED) PHYSICAL CHANGE

Characteristics of Chemical Changes Chemical Changes New Substances with Different properties Involves a Chemical reaction Could be use of heat To make new substances Can only be Undone by Another Chemical Change

Demo of Chemical and Physical Changes (Don’t Do At Home!) PdcUghttp:// PdcUg