warm up 9/19 1. suppose you have a sample of an unknown mineral. its mass is 50 g and it has a...

Warm Up 9/19Warm Up 9/19

1. Suppose you have a 1. Suppose you have a sample of an unknown sample of an unknown mineral. Its mass is 50 g mineral. Its mass is 50 g and it has a volume of 100 and it has a volume of 100 cm3. What is its density?cm3. What is its density?

2. Copper has a density of 8.9 2. Copper has a density of 8.9 g/cm3. If there is a 6 cm3 g/cm3. If there is a 6 cm3 sample of copper, what is sample of copper, what is its mass? its mass?

Physical Properties of MatterPhysical Properties of Matter

Can be observed using the 5 senses.Can be observed using the 5 senses.

Help to identify a material and Help to identify a material and determine how it can be used.determine how it can be used.

Ex: appearance, texture, color, odor, Ex: appearance, texture, color, odor, melting point, boiling point, density, melting point, boiling point, density, solubility, taste, and many others. solubility, taste, and many others.

Melting and Boiling PointsMelting and Boiling Points

Both are physical properties!!!Both are physical properties!!!

Melting Point:Melting Point: The temperature and The temperature and pressure at which a solid becomes a pressure at which a solid becomes a liquidliquid

Boiling Point:Boiling Point: The temperature at The temperature at which a liquid becomes a gas.which a liquid becomes a gas.

Chemical PropertiesChemical Properties

Describe how a substance will change into Describe how a substance will change into a new substance (react)a new substance (react)

Are not easy to observeAre not easy to observe

Examples: Examples: Does the metal rust?Does the metal rust? Does this mineral react with water? Does this mineral react with water? Baking soda vs. sugar (mixed with Baking soda vs. sugar (mixed with

vinegar)vinegar)

Chemical PropertiesChemical Properties ReactivityReactivity is a chemical property is a chemical property

which describes how an element or which describes how an element or compound reacts with things like compound reacts with things like oxygen, acid or water.oxygen, acid or water.

FlammabilityFlammability is another (the ability to is another (the ability to burn).burn).

Substances all have chemical Substances all have chemical properties even though you can’t see properties even though you can’t see them! them!

Physical and Chemical Properties Physical and Chemical Properties Song Song

http://www.youtube.com/watch?v=uJOGy0dgmUU

Physical ChangesPhysical Changes

What the substance is made of does What the substance is made of does NOT change. NOT change.

Ex. If you break a piece of chalk in Ex. If you break a piece of chalk in two, it is still chalk (chemical two, it is still chalk (chemical properties remain unchanged)properties remain unchanged)

Physical ChangesPhysical Changes After a physical change, a substance might After a physical change, a substance might

look different, but has the same atomic look different, but has the same atomic structure. structure.

Important to remember that all changes of Important to remember that all changes of state are physical changes because the state are physical changes because the identity of the substance stays the same (ex. identity of the substance stays the same (ex. water to ice)water to ice)

Dissolving is a physical change (sugar in Dissolving is a physical change (sugar in water) because the sugar molecules do not water) because the sugar molecules do not change.change.

Changes in state from solid to liquid to gas are physical changes; it is still the same substance…

Physical Changes Physical Changes

Chemical ChangesChemical Changes

When a substance changes what it is When a substance changes what it is made of by bonding with another made of by bonding with another substance.substance.

In a chemical change you might In a chemical change you might notice odor, fire, light or rustingnotice odor, fire, light or rusting

Ex. Digestion, sour milk, baking a Ex. Digestion, sour milk, baking a cake, skunk, camp fire, fireworks cake, skunk, camp fire, fireworks

Chemical Changes Chemical Changes Form new substances that have different Form new substances that have different

properties from the original properties.properties from the original properties.

Ex. When you bake a cake, you start with Ex. When you bake a cake, you start with several different ingredients, but after it is several different ingredients, but after it is done baking all are mixed together and done baking all are mixed together and look very different from what you started look very different from what you started with. with.

Chemical changes are known as “chemical Chemical changes are known as “chemical reactions.” reactions.”

Chemical Changes Chemical Changes

Easy to detect (change in smell, Easy to detect (change in smell, color, fizzing, foaming, heat or light)color, fizzing, foaming, heat or light)

Ex. You can see that the batter has Ex. You can see that the batter has hardened into cake, you can smell it hardened into cake, you can smell it and sometimes you can hear it being and sometimes you can hear it being cooked.cooked.

Chemical ChangesChemical Changes

Cannot be reversed by physical Cannot be reversed by physical changeschanges

Cannot “unbake” a cake by separating Cannot “unbake” a cake by separating the ingredients.the ingredients.

Some chemical changes can be Some chemical changes can be reversed by other chemical changes. reversed by other chemical changes.

Ex. Water can be split into H and O Ex. Water can be split into H and O using an electric current to initiate a using an electric current to initiate a reaction.reaction.