MATTER Essential Question: Are all objects composed of matter?

What is matter? It is anything that has mass and takes up space. Matter can be small or large All matter is made up of atoms and molecules Everything around you is made up of matter--- You, the air around us, microbes, even chocolate cake Objects can be made up of different atoms Example: Gold is made up of Gold atoms Salt is made up of two different atoms: sodium atoms and chloride atoms Essential Question: Are all objects composed of matter?

States of Matter Solid Liquid Gas

Solid  definite volume  definite shape  atoms are packed together in fixed positions  strong attractive forces between atoms  only vibrate in place

Liquid  definite volume  indefinite shape  atoms are close together  atoms can overcome attractive forces to flow

Gases  indefinite volume and shape  atoms move quickly  atoms are far apart  weak attractive forces  vapor refers to the gaseous state of a substance that is a solid or liquid at room temperature.

Why are properties important? All substances have properties that we can use to identify them. In a similar way matter has properties – There are physical and Chemical Properties Essential Question: How can physical and chemical properties be used to identify matter?

Physical Properties A physical property is a characteristic that can be observed or measured without changing the sample’s composition. Examples of physical properties are: color, smell, freezing point, boiling point, melting point, infra-red spectrum, attraction (paramagnetic) or repulsion (diamagnetic) to magnets, opacity, viscosity and density. Essential Question: How can physical and chemical properties be used to identify matter?

Physical Properties- Activity Provide a minimum of 3 physical properties for the following: Essential Question: How can physical and chemical properties be used to identify matter? ItemPhysical Property Sugar Baking Soda Water

On a side note, several physical properties of matter require the use of MATH. So what does this mean? Physical properties such as density, mass, or length require that you express those numbers using the correct number of Significant Figures.

Physical Properties can be classified further as being extensive or intensive - Extensive Properties: DO depend on the amount of matter present. * Example: Mass, weight, volume, length -Intensive Properties: do NOT depend on the amount of the matter present. * Example: Color, odor, hardness, melting/freezing point, boiling point, density, malleability, luster

Density Density = 135 g = 2.70 g/mL 50 mL Density = mass (g) volume (mL ) Volume can either be determined by the water displacement method or V = L x W x H (units will be cubic centimeters cm 3 ) Example: Calculate the density in g/mL of aluminum if a 50 mL block weighs 135 g Solution: Apply the definition:

Density Activity Find the density of the cube g What is the mass? ________ What is the volume?______ What is the density in correct significant figures?________ Find the density of the rock 7.64 g What is the mass?_____ What is the volume?____ What is the density in correct significant figures?_____

Chemical Properties A chemical property is the ability of a substance to combine with or change into one or more other substances. Examples of chemical properties are: heat of combustion, reactivity with water, PH, ability of iron to form rust when combined with air Essential Question: How can physical and chemical properties be used to identify matter?

Chemical Properties-Activity Demo Baking soda with vinegar Copper with ammonia Essential Question: How can physical and chemical properties be used to identify matter?

Physical Changes in Matter change in a substance that doesn’t change the identity of the substance Ex. grinding, cutting, melting, boiling  Includes all changes of state (physical changes of a substance from one state to another)

Changes of State

Chemical Changes in Matter a change in which a substance is converted into a different substance Reactants = Products doesn’t change the amount of matter present (According to the law of conservation of mass: Mass is neither created nor destroyed; it is conserved.)

Signs of Chemical Change  Energy is always absorbed or given off  Change in color or odor  Production of a gas  Irreversibility

Chemical or Physical? Cookies are baked Water boils Salt dissolves in water Milk spoils A metal chair rusts Paper is torn A tree burns down