1. Elements, Compounds, and Mixtures
8th Grade Science
8.P.1.1 Classify matter as elements, compounds, or mixtures based on how the atoms are packed together in arrangements.

2. Essential Questions
How does the arrangement of atoms affect the classification of matter?
What is the difference between elements, compounds, and mixtures?

3. How do we classify matter?
What is an element?
A pure substance that is made up of only one kind of atom  H, He, O2
Organized on the periodic table
Represented with a chemical symbol
What is a compound?
A pure substance made up of two or more elements that have been chemically combined
Represented using a chemical formula  C6H12O6, NaCl
What is a pure substance?
Any substance that cannot be physically broken down into simpler substances
Includes both elements and compounds

4. What are mixtures? The physical combination of 2 or more substances
Mixtures are NOT chemically combined
Mixtures can be separated by physical means (filtration, evaporation, distillation)
Mixtures are divided into two groups
Heterogeneous
A mixture that is unevenly distributed
Homogeneous
A mixture that is evenly distributed

5. Comparing Elements, compounds, and mixtures
Creating a foldable:
Fold a blank sheet of paper in half hamburger style
Next, fold the half size into thirds
Carefully cut along the folds of only the top half of folded paper so that you have 3 flaps, then glue down in your notebook

6. Label each flap with the following information:
Elements
Compounds
Mixtures
A pure substance
In an element, all atoms are identical and share the same physical and chemical properties
Represented with a chemical symbol
A compound is a combination of 2 or more elements joined by chemical bonds
Represented with a chemical formula
A combination of pure substances
A mixture is composed of element(s) and/or compound(s)
Label each flap with the following information:
Flap 1 Title: Elements
Flap 2 Title: Compounds
Flap 3 Title: Mixtures

7. Elements Behind “Elements” Flap Inside “Elements” Flap
Elements are organized on the periodic table
There are over 100 known elements
Elements are represented with a chemical symbol.
The symbol is at least one letter; the first letter is always capitalized
Example: H (Hydrogen) & He (Helium)
Element examples:
Mg (Magnesium)
C (Carbon)
S (Sulfur) or S8
Some elements are diatomic (2 atoms); they occur in nature in groups of two
H2, O2, Br2, Cl2

8. Can it have two or more types of atoms? Can it have one type of atom?
Compounds
Behind “Compounds” Flap
What is the difference between a molecule and a compound?
Type of Substance
Can it have two or more types of atoms?
Can it have one type of atom?
Can it be an element?
Molecule
Yes
Compound
Yes (it must!) No
Inside “Compounds” Flap
There are millions of compounds!
Examples: H2O, H2O2, FeO, CH3
All compounds are molecules, but not all molecules are compounds  O2 is a molecule, but it’s not a compound

9. Mixtures Behind “Mixtures” Flap Inside “Mixtures” Flap
Homogeneous Mixtures
Heterogeneous Mixtures
These mixtures are evenly distributed and may look like pure substances because they are completely mixed into a single phase
Also called solutions – contain a solute (the substance being dissolved) dissolved in a solvent (the substance doing the dissolving)
Examples: salt water, Kool-aid, brass
These mixtures are not evenly distributed
The substances are considered insoluble because one substance will not dissolve in the other
Examples: oil and water, Chex mix, chicken noodle soup

10. Venn Diagram – Comparing elements, compounds, and mixtures
Place the letter for each description in its location on the Venn Diagram
Pure substance
Only one type of atom
Two or more types of atoms
Always homogeneous
Can be homogeneous
Matter
Can be two or more phases
There are about 100 different ones
Two elements joined by chemical bonds
Can be separated by physical change
Can be broken down by chemical change
B, H
A, D
E, F
K, I
G, J C