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 * __Chem 142__**

CHAPTER 1-The Chemical World
explains scientific method, all things composed of atoms and molecules. Quick Vocab: Law of conservation of mass: "matter is neither created nor destroyed"

__CHAPTER 2-Measurement and Problem Solving__
Scientific Notation: A positive exponent means 1 multiplied by 10 //n// times. 10^0=1 10^1=1x10=10 ..and so on A negative exponent (-//n//) means 1 divided by 10 //n// times. 10^1=1/10 10^-2=1/10x10=0.01 ...and so on __**To express a number in scientific notation**__ 1.)Move the decimal point to obtain a number between 1 and 10. 2.)Write the result multiplied by 10 and raised to the number of places you moved the decimal. Example: 350 should be written as 3.5 x 10^2 or as 3.50 x 10^2 Exact numbers have an unlimited number of sig figs. CHAPTER THREE-MATTER AND ENERGY CONT>>
 * __ Significant Figures: writing numbers to reflect precision __**
 * TO DETERMINE THE NUMBER OF SIGNIFICANT FIGURES IN A NUMBER, FOLLOW THESE RULES:**
 * 1) All nonzero digits are significant. Examples: ** 1 **.0** 5 ** 0.0** 11 **0
 * 2) Zeros between two numbers are significant. Examples: 4. 0 2 0 8  5 0. 1
 * 3) Zeros after a decimal point are significant. Examples: 5.1 0 3 .00
 * 4) ​ Leading Zeros AKA zeros to the left of the first nonzero number are NOT significant. Example: 0.0005 has only one sig fig, the #5.
 * 5) Zeros at the end of a number but before or lacking a decimal point are ambiguous and should be written using scientific notation.
 * __ Exact Numbers __**