Properties of Matter

Objectives Distinguish between the physical and chemical properties of matter, and give examples of each Perform calculations involving density Explain how materials are suited for different uses based on their physical and chemical properties, and give examples Describe characteristic properties, and give examples

Physical vs. Chemical Properties Physical properties are those that you can observe or measure Examples: color, shape, odor, texture, mass, volume, density Chemical properties are those that describe how a substance reacts or changes into a new substance Examples: flammability, rusting, reactivity, combustible

Physical Properties Describe matter Found by observing or measuring Remain constant for pure substances Important physical Properties: Melting point Boiling point Hardness Strength Ability to conduct electricity, magnetism, or heat Physical State

Physical Properties 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 Physical State: solid, liquid & gas Density: is the measure of how much matter is contained in a certain volume of a substance

Density Is found by dividing a substance’s mass by its volume It determines whether something will sink or float Its units are g/cm3 Questions: Does air have mass? Can we find its density? Lets play will it sink or float!

Density Problems If 10.0 cm3 of ice has a mass of 9.17 g, what is the density of ice? D = m/V = 9.17g/10.0 cm3 = 0.917 g/cm3

Density Problems The density of oak wood is 0.7 g/cm3 If a 35 cm3 piece of wood has a mass of 25 g is the wood likely to be oak? D = m/V = 25 g/35 cm3 = 0.71 g/cm3 Mostly likely it is oak.

Density Problems The density of silver is 10.5 g/cm3. A bracelet made of silver has a volume of 1.12 cm3. What is the bracelet’s mass? D = m/V m = D ∙ V = 10.5 g/cm3 ∙ 1.12 cm3 = 11.8 g

Chemical Properties Describe how a substance will react Chemical properties also describe how a substance changes into a new substance Some substance react very easily combining into compounds Example: Magnesium Others rarely combine with other elements Example: Gold

Chemical Properties Rusting: oxygen reacts with some metals forming a new substance known as an oxide Reactivity: the ability of a substance to combine chemically with another substance Flammability: the ability to burn Combustibility: the ability to combust/explode