1. Eighth Grade Science
Mrs.Nelson

2. STARTER 1/17 and 1/18 Welcome Back!
Distinguish between an element and a compound. Explain two identifying characteristics of each.
Dissect the term subscript. Examine the prefix and root word. Predict what the term represents.
STANDARD FOCUS:
SPI
Recognize that all matter is made of atoms.
SPI
Classify common substances as elements or compounds based on their symbols or chemical formulas.
SPI
Use the periodic table to determine the properties of an element.

3. 4 Corners Corners are: 1. Element 2. Compound 3. Heterogeneous mixture
Take the card you have been given.
Determine the type of matter represented on your card.
Move to the location which matches your material.
Discuss with your group whether you belong. Remain or move based on group input.
Prepare to defend your judgment.
Corners are:
1. Element
2. Compound
3. Heterogeneous mixture
4. Homogeneous mixture

4. Matter Types Foldable Fold paper as instructed.
Cut flaps on both sides.
Label
Record the following for each of
the four matter types:
Definition
Examples with formulas
Distinguishing characteristics

5. Can it be separated by physical means?
A. Matter Flowchart
MATTER
yes no
Can it be separated by physical means?
PURE SUBSTANCE
MIXTURE
Is the composition uniform? no
yes
Can it be decomposed by chemical means? no
yes
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element

6. B. Pure Substances Element matter composed of identical atoms
EX: copper, Au

7. B. Pure Substances Compound
matter composed of 2 or more elements in a fixed ratio
properties differ from those of individual elements
EX: salt (NaCl)

8. C. Mixtures Homogeneous Mixture (Solution)
Variable combination of 2 or more pure substances.
Homogeneous Mixture (Solution)
even distribution of components
very small particles
particles never settle
EX: saline solution

9. C. Mixtures Heterogeneous Mixture uneven distribution of components
Can see all components
EX: trail mix

10. Chemical Formulas Shorthand method to name pure substances.
Always show the fixed composition
Never applied to mixtures- WHY?

11. What is it? Elements are simply represented by their symbol.
When two different atoms bond they make a compound.
A chemical formula names the new substance that is made.
Ex: Na and Cl make Sodium Chloride
New substances have new characteristics.
Shorthand way to write names is used in science.
NaCl is the chemical formula for sodium chloride.

12. NaF2 Parts and Pieces Element symbols represent the elements present
Subscripts are those little numbers attached to symbols- they cannot ever change
NaF2

13. Compound and molecule vs element
You can read a chemical formula to determine the nature of a substance
Compounds show more than one item by multiple symbols or subscripts
CO2, H2O, HCl
You can identify a single element by seeing just one symbol or lack of subscripts.
Ag, N, Cu

14. STOP and THINK Remember:
Elements are pure substances made of only one type of atom.
Compounds are unique substances too, but with two or more atoms chemically bonded together.
Mixtures have no real set composition, no bonds, and can be physically separated.
Chemical formulas are like recipes to determine the composition of a compound.

15. SUMMARY Pt O O2 Water Air Salt water
Identify the following in your journal as mixture, element, or compound.
Pt O
O2 Water
Air Salt water