Significant Figures

Significant Figures...

So, today in the wonderful world of pre-ap chemistry, we learned all about significant figures. It's actually not as hard as it looks... once you finally get it down. Allow me to explain.


Rule #1) You can estimate 1 digit past the calibration on the instrument used.
Rule #2) understand that significant digits indicate accuracy, not quantity.
Rule #3) When rounding, round 4 and below down, and 5 or above up.
Rule #4) The last digit in a measurement is ALWAYS uncertain.

Learning Through Example...

500 mL
Has 1 significant digit... the 5

560 mL
Has 2 significant digits, the 5 and the 6

555.5
Has 4 significant digits.

0.004004500

The First zero before the decimal place, 0.004004500 is not significant, it is only there to show that the larger number is a decimal.
The two zeros following the decimal, 0.004004500 are not significant, and their only purpose is to hold the place for the larger number as a decimal.
The remaining numbers are significant, but we will focus on these for now. 0.004004500, the two 4's and the 5 are significant because they are actually digits.
The two zeros that are locked in between the numerals, 0.004004500, are significant because of their position in being locked in.
The two zeros trailing at the end of the number, 0.004004500 are significant because they show accuracy within the number.

Comment if you have questions!! It's a little confusing at first, but the more examples, the better!!




References:
(n.d.). Retrieved October 23, 2015, from https://jahschem.wikispaces.com/file/view/sig-figs-examples.png/445639706/sig-figs-examples.png