C HAPTER Properties of Matter

B ELL RINGER Compare and contrast atoms and molecules. Explain why elements and compounds are pure substances while a homogeneous mixture is not. Explain why carbon and copper are classified as elements.

K EY I DEAS What is the difference between chemical and physical properties?

R EVIEW Explain what a molecule is. Provide an example. State the difference between a molecule and a compound.

P HYSICAL P ROPERTIES Physical properties are characteristics that can be observed without changing the identity of the substance. Examples Color Mass Shape Volume Density

P HYSICAL P ROPERTIES Physical properties can help us identify substances

I DENTIFY THE FOLLOWING IMAGES

P HYSICAL P ROPERTIES CAN BE OBSERVED OR MEASURED The physical state that the substance is in is also a physical property Solid Liquid Gas

P HYSICAL P ROPERTIES Melting Point – the temperature and pressure at which a solid becomes a liquid Boiling Point – the temperature and pressure at which a liquid becomes a gas

Each substance has its own melting point and boiling point which allows us to predict what substance it is. This also allows us to predict the purity of the substance

SubstanceMelting Point ( o C)Boiling Point ( o C) Gold Iron Mercury Nitrogen Oxygen NaCl Water0100

D ENSITY Density is a physical property Density allows us to identify the purity of a substance Example- Archimedes Crown

D ENSITY Density = Mass/Volume It is a measure to how many atoms are in a certain amount of space How much “stuff” is in an object

W HICH OF THIS IMAGES IS MORE DENSE ? E XPLAIN

C ONNECTING C ONCEPTS If Fluorine has a molar mass of g/mol and Iron has a molar mass of g/mol, which element is more dense? How many atoms are in one mole of each substance?

If the number of atoms is the same, what must of changed for their density to be different?

C HEMICAL P ROPERTIES Chemical Properties describe how a substance changes into a new substance This can by combining with other elements or by breaking apart into new substances

C HEMICAL P ROPERTIES Flammability – or the ability to burn Reactivity – the capacity of a substance to combine with another substance