1. Review
7th Grade

2. What is the problem with not having specific measurements or procedures in an experiment?

3. Variables Independent Variable – the one the scientist changes
Example: amount of sunlight
Dependent Variable – changes based on independent
Example: amount of growth
Constants – they stay the same in all of them
Example: type of plant, how much water, the pot, soil (type and amount), fertilizer (if you use any), temperature (whether outside or inside)
Control Variable – used for measurements; the one you keep regular (standard) in order to see change
Example: one plant kept in sun all day
*** Only one variable tested at a time for accurate results ***

4. If I just found a pure substance on the ground, what are some things I could use to determine what it is? (Be specific)

5. Things I could NOT use to determine what it is: Sound Shape Size
Things I could use to determine what it is:
Hardness
Malleability
Boiling point
Freezing point
Melting point
Flammability
Conductivity
Texture
Color
Reactivity/Oxidation
Odor (smell)
Taste
Luster
Streak
Density – mass/volume (how much matter is in a given space)
State of matter at certain temperature
Thickness
Molecular Mass
Things I could NOT use to determine what it is:
Sound
Shape
Size
Roll-ability
Volume – how much space it takes up
Mass – how much matter there is
Weight – the gravitational force acting on an object
State of matter

6. How would mass effect an items boiling point?
Would it also effect its freezing and melting point?

7. Can a chemical reaction be reversed?

8. Some chemical changes can be reversed, but only by other chemical changes. For example, to undo tarnish on copper pennies, you can place them in vinegar.

9. When a chemical reaction occurs, what happens to the atoms that make up molecules? Do they disappear?