What is Chemistry??

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

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

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

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

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

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.**

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!

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

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

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.

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