1. Metric System

2. Measurement Measurement is the basic part of science
Imagine how you would measure the length of an object, mass of a substance, or distance from one place to another without measurements
Numbers and units are used to make measurements
To make practical measurements, a measurement standard must be used
Standard is a fixed quantity used by everyone when measuring

3. SI System
Scientists all over the world use one universal system, SI System
SI=International System of Units
All SI units and standards are agreed upon and understood by scientists all over the world
In the SI system, prefixes are used to make the basic units larger or smaller by multiples of ten

4. SI Base Units Length=meter (m) Mass=kilogram (kg)
Temperature=kelvin (K)
Time=seconds (s)
Amount of Substance=mole (mol)
Electric Current=ampere (A)

5. Metric Prefixes Prefix Symbol Meaning Multiply Unit By Giga- G
Billion (109)
1,000,000,000
Mega- M
Million (106)
1,000,000
Kilo- k
Thousand (103)
1000
Deci- d
Tenth (10-1)
0.1
Centi- C
Hundredth (10-2)
0.01
Milli-
Thousandth (10-3)
0.001
Micro-
Millionth (10-6)
Nano- N
Billionth (10-9)

6. SI for Temperature Kelvin scale is the SI unit for temperature
Kelvin=°C + 273
Zero Kelvin is the same as absolute zero
Point in which all molecular motion stops

7. Limits of Measurement Precision Accuracy
Gauge of how exact a set measurements are to one another
More precision=more significant figures
All the digits that are known in a measurement, plus the last digit that is estimated
Accuracy
Closeness of a measurement to the actual value of what is being measured

9. Significant Figures in Measurements
Significant figures in measurements include all of the digits that are known, plus a last digit that is estimated
Measurements must always be reported to the correct number of significant figures because calculated answers often depend on the number of significant figures in the values used in the calculation
Also known as sig figs

10. Rules For Determining Whether a Digit is Significant
1) Every nonzero digit in a reported measurement is assumed to be significant.
Ex) m, m, and 714 m all have 3 sig figs
2) Zeros appearing between nonzero digits are significant.
Ex) m, m, and m all have 4 sig figs
3) Leftmost zeros appearing in front of nonzero digits are not significant. They act as place holders
Ex) m, 0.42 m, m all have only 2 sig figs

11. Rules For Determining Whether a Digit is Significant
4) Zeros at the end of a number and to the right of a decimal point are always significant.
Ex) m, m, and m each have 4 sig figs
5) Zeros at the rightmost end of a measurement that lie to the left of an understood decimal point are not significant if they serve as placeholders to show the magnitude of the number.
Ex) The zeros in 300 m, 7000 m, and 20,000 are not significant. The sig fig values for these numbers is one

12. Density Density is a physical property
Density is the mass of a material per unit of volume
Standard Unit=g/cm3
The density of a substance may be used to help identify the substance

13. Density 13.6 g/cm3 21.5 g/cm3 2.7 g/cm3 Platinum Platinum Mercury
Aluminum
Platinum
Platinum
Mercury
Mercury
13.6 g/cm3
21.5 g/cm3
2.7 g/cm3

14. Density Equation
Using algebrae, we can solve for all three substances (density, volume, and mass) by manipulating the equations:
Density=Mass/Volume
Mass=Density X Volume
Volume=Mass/Density

15. Volume Volume is the amount of space an object takes up 1 cm3=1 mL
Volume=Length x Width x Height

16. Problem 1 A piece of copper has a mass of 57. 54 g. It is 9
Problem 1 A piece of copper has a mass of g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3).