Into to Chemistry: Significant Figures

1. It’s really not that bad Into to Chemistry:Significant Figures

2. Significant Figures • The # of digits reported for the value of a measured or calculated quantity, indicating the precision of the value • 4 Rules govern Sig Figs

3. Sig Fig Rule 1 • Any number that isn’t zero is significant. Any zero that’s between two numbers that aren’t zeros is significant. • 1, 2, 3, 4, 5, 6, 7, 8, & 9 • 101

4. Sig Fig Rule 2 • Any zero that’s before all of the nonzero digits is insignificant, NO MATTER WHAT. • 000.09 • But Mr. Milo, don’t those zeros tell me something? Yes and no. The reason that you don’t count these numbers as significant is mainly because of rule 4, which we’ll talk about after…

5. Sig Fig Rule 3 • Any zero that’s after all of the nonzero digits is significant only if you see a decimal point. If you don’t actually see a little dot somewhere in the number, these digits are not significant. • 900. verses 900

6. Sig Fig Rule 4 • When you write numbers in scientific notation, only the part before the “x” is counted in the significant figures. • Example, 2.39 x 10-4has three significant figures because we only worry about the “2.39” part.

7. Rounding Sig Figs • Multiplication and Division: • Round to the least # of significant figures in the problem • Addition and Subtraction • Round to the least # of decimal places in the problem

8. See that wasn’t too bad • Now how about some practice • http://woodridge.k12.oh.us/ourpages/users/dweaver/Chemistry/PracticeWorksheets/MiscellaneousWorksheets.html