CHEM 1101 Lecture Notes - Lecture 7: Significand, Scientific Notation, Significant Figures
30 Apr 2018
School
Department
Course
Professor
Math & Measurement
January 5, 2018 7:04 PM
1.1 Exponential and Scientific Notation
1.2 Significant Figures
○ Significant figures tell how precisely a measured value is known (not accuracy)
○ If not specified, assume the true value or minus 2 (+-2) in the last significant digit
○ Eg. 26.952 kg -> 26.952 + 0.002 kg
Prefixes:
••1000m
103 = 1 km 1km x 103 = 1000m (base units)
÷
Rules:
○ All non-zero digits are significant
○ Any zeros between two significant digits are significant
○ Terminal zeros are significant only if there is a decimal
○ Leading zeros are NEVER significant.
○ Round normally but remember 700 has one significant digit so add decimal.
Multiplication and Division:
○ Keep fewest number of significant digits even for scientific notation
○ Eg. 2.00 x 4.0 = 8 -> 8.0
Addition and Subtraction:
○ When in standard notation: Keep fewest number of decimal places
○ Eg. 12.34 + 1.1 = 13.44 -> 13.4
○ Eg. 5.69 + 34. = 39.69 -> 40
• When in scientific notation:
○ Convert to standard notation or make exponent same value
• Going from -6 to -4, move decimals to right (10 exponent is greater so significand gets smaller)
• Going from -6 to -8, move decimals to left (10 exponent is smaller so significand gets greater)
○ Keep fewest number of decimal places
○ In decimals, when number comes to 0 first
We don't know digits after 34. so don’t keep any decimals in final answer.
this notebook
Document Summary
Significant figures tell how precisely a measured value is known (not accuracy) If not specified, assume the true value or minus 2 (+-2) in the last significant digit. 103 = 1 km 1km x 103 = 1000m (base units) Any zeros between two significant digits are significant. Terminal zeros are significant only if there is a decimal. Round normally but remember 700 has one significant digit so add decimal. Keep fewest number of significant digits even for scientific notation. When in standard notation: keep fewest number of decimal places. = 39. 69 -> 40: when in scientific notation: In decimals, when number comes to 0 first.
