# 1: Measurement

- Page ID
- 222709

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- 1.1: Expressing Numbers
- Standard notation expresses a number normally. Scientific notation expresses a number as a coefficient times a power of 10. The power of 10 is positive for numbers greater than 1 and negative for numbers between 0 and 1.

- 1.2: Significant Figures - Writing Numbers to Reflect Precision
- Uncertainty exists in all measurements. The degree of uncertainty is affected in part by the quality of the measuring tool. Significant figures give an indication of the certainty of a measurement. Rules allow decisions to be made about how many digits to use in any given situation.

- 1.3: Significant Figures in Calculations
- To round a number, first decide how many significant figures the number should have. Once you know that, round to that many digits, starting from the left. If the number immediately to the right of the last significant digit is less than 5, it is dropped and the value of the last significant digit remains the same. If the number immediately to the right of the last significant digit is greater than or equal to 5, the last significant digit is increased by 1.

- 1.4: The Basic Units of Measurement
- Metric prefixes derive from Latin or Greek terms. The prefixes are used to make the units manageable. The SI system is based on multiples of ten. There are seven basic units in the SI system. Five of these units are commonly used in chemistry.

- 1.5: Problem Solving and Unit Conversions
- During your studies of chemistry (and physics also), you will note that mathematical equations are used in a number of different applications. Many of these equations have a number of different variables with which you will need to work. You should also note that these equations will often require you to use measurements with their units. Algebra skills become very important here!

- 1.6: Solving Multistep Conversion Problems
- Sometimes you will have to perform more than one conversion to obtain the desired unit.