1. What is Chemistry??

2. Chemistry
Definition: study of the composition of matter and the changes that matter undergoes.
Well what is matter?

3. Matter Definition: anything that has VOLUME & MASS
Things that are NOT matter:
Heat
Light
Radio waves
Magnetic fields
VOLUME: amount of space an object takes up
MASS: Amount of matter an object contains

4. The “Sub”disciplines of Chemistry
5 Branches of Chemistry:
ORGANIC CHEMISTRY: carbon containing
INORGANIC CHEMISTRY: non-living
BIOCHEMISTRY: processes in organisms
ANALYTICAL CHEMISTRY: composition of matter
PHYSICAL CHEMISTRY: changes in matter

5. TERMS TO KNOW MACROSCOPIC MICROSCOPIC SUBMICROSCOPIC
large enough to be seen with the unaided eye
MICROSCOPIC
can only be seen using a light microscope
SUBMICROSCOPIC
cannot be seen even with the most powerful light microscope
Atoms ( . = 1 x 1020 atoms)
Scanning tunneling microscope (STM): produces images on a computer screen of the locations of individual atoms

6. SCIENTIFIC METHOD A systematic approach for learning about the world
5 main steps….

7. Scientific Method
1. OBSERVE an event or process. State the problem. Gather background information on the problem.
2. FORM A HYPOTHESIS (suggested explanation for observed events.)
3. PERFORM EXPERIMENTS to test hypothesis.**

8. Step 3. Performing Experiments
Variables – factors that may change
1. Independent Variable (Manipulated Variable):
The variable that is changed by the scientist.
Ex: Amount of fertilizer
2. Dependent Variable (Responding Variable):
A variable that changes as a result of the independent variable.
Ex: How high the plant grows
3. Controlled Variable:
A variable that is held constant so that it does not influence the outcome of the experiment.
Ex. Amount of water, sunlight, type of soil
TEST ONLY ONE VARIABLE AT A TIME!

9. Step 3. Performing Experiments
Should have:
Control Setup
Exactly like the experimental setup except that it DOES NOT contain the variable of interest. The control setup is used for comparison.
Multiple Trials
To ensure accuracy

10. Scientific Method … continued
4. RECORD AND ANALYZE DATA
Data – recorded observations and measurements
Create a data table and/or graph to better visualize data
Analyze – make calculations, use statistics
5. DRAW CONCLUSIONS
Create a theory to explain your results

11. Hypotheses, Theories, Laws
Hypothesis: testable prediction to explain observations
If I drop 2 objects with different weights, will they hit the ground at the same time?
Theory: an explanation based on many observations and supported by the results of many experiments; organizes a large body of knowledge
Why do objects fall towards the ground?
Why does the sun rise?
Scientific Law: fact of nature that is observed so often that it becomes accepted as truth
All objects (regardless of weight) fall at the same rate.
The sun will rise every morning.

12. Often the most valuable experiments “fail”
If you do not get the result that you expect, then you look critically at the experiment to see if you made a mistake.
Is it reproducible?
Is your hypothesis correct?
Period 2 stopped here before lab