Units of Measurement We measure everything! see table 1.1 and 1.2

Examples of Measurements will we use numbers that big/small in class? yep! the mole

the mole 602,213,700,000,000,000,000,000 particles or x particles scientific notation!

Scientific Notation a way to write really big numbers

How to go to sci. notation Numbers bigger than ten will have positive exponents that will equal how many times decimal moved to the left = 3.6 x 10 4 Numbers smaller than ten will have a negative exponents that will equal how many times it moved to the right = 8.1 x 10 -3

Practice Write in scientific notation m g 9.14 x 10 2 m 1.54 x g

How to go from sci. notation Positive exponent = decimal moves to right 8.25 X 10 4 = Negative exponent = decimal moves to left 1.2 X =.0012

Practice Write in scientific notation X 10 5 L X m L.065 m

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which measurement is best? g x 10 3 g x 10 3 g

Significant Figures= digits recorded in measuring the more sig figs the greater the certainty

Rules 1.All nonzeroes are significant 2.Zeroes in-between are significant 3.Zeroes to the left are not significant 4.Zeroes to the right are not significant unless they follow a decimal. 5.All numbers in scientific notation are significant 6.Exact numbers are obtained by counting or definitions such as 1 in = 2.54 cm, and are considered infinite in significance

Practice How many sig figs are in the following? m J 3.10 km 4.60 sec = 1min x 10 8 ng infinite! 3

so…which measurement is best? g x 10 3 g x 10 3 g

Adding and Subtracting Always use the least significant decimal place. example: = = round up = or X 10 -2

Practice complete the following g g + 19 g = L L = m m m = 43 g L m

Multiplying and Dividing All ways go by the least number of significant figures. examples: X 1.1 = No 1400 or 1.4 x 10 3

Practice complete the following cm x 1.7 cm = kg ÷ = m x 3.21 m x m = 7.3 cm kg 32.4 m 3

Combining the math Follow order of operations X.033 = X.033 = 2 x (1 sig fig) 4.54

Practice  = or x 10 2 = = =