Unit 2: Chemistry

Lesson 2: Classifying Matter

Essential Questions:1.) What is matter made of?2.) What are two types of mixtures?

What is matter made of?

A substance that cannot be broken Element down into any other substances bychemical or physical means

Elements are the simplest substancesThey are identified by physical and chemical propertiesThey are represented by one or two letter symbols

Each element has:

physical and chemical properties

one or two letter symbols

The basic particle from which Atomall elements are made

All matter is made of atomsIt has a positively charged center, or nucleus, surrounded by a “cloud” of negative charge Elements have different properties because their atoms are different

Atom

Positively charged nucleus and smaller particles

Cloud of negative charge

A force of attraction between Chemical bondtwo atoms

A group of two or more atoms Moleculesheld together by chemical bonds

The atoms can be atoms of the same element or different elements

Water is a molecule made up of an oxygen atom chemically bonded to two hydrogen atoms.

Oxygen molecules are made up of two oxygen atoms chemically bonded.

Oxygen atom

Chemical bond

In Class Activity

A substance made of two or more Compoundelements that are chemically combined in a set ratio

This formula shows the elements Chemical Formula in the compound and the ratio ofatoms

The chemical formula for water is H2O. There are two hydrogen atoms and 1 oxygen atom in water.

When elements combine, they form compounds with properties different from those of the elements.

Chemistry Textbook page 11

What are the two types of mixtures?

Two or more substances that are Mixturetogether in the same place, but their atoms are not chemically bonded

Each substance in a mixture keeps its own properties The parts can be separated

A salad is a mixture. It includes lettuce, carrots, tomatoes, onions and croutons. You can separate the items.

In this mixture, you can usually see Heterogeneous the different parts and theycan be separated

In this mixture, the substances Homogeneous are so evenly mixed that you can’t see the different parts

MixturesWhich of these foods are heterogeneous and which are homogeneous?

How can you separate a mixture?