1. SI System of Measurement ….Common chemistry units
Base Units: Symbol
meter (length) m
kilogram (mass) kg
second (time) s
kelvin (temperature) K
mole (amount of substance) mol

2. Some additional units Volume: cubic centimeter, cm3, cc
liter, L milliliter, mL
Density: g/cm3, g/mL, g/L
Energy: calorie, cal joule, J
Pressure: kiloPascal, kPa
mm of Hg
atmosphere, atm.

3. kilo… is a large unit (k)
Means 1000x (103)
1 kilometer = 1000 meters
1 kilojoule = 1000 joules
1 kg = 1000g etc…
2 Conversion factors:
1km m
1000m km

4. deci… is a smaller unit (d)
Means 1/10 or (10-1)
1 decimeter is .1meter
There are 10 decimeters in 1 meter
2 Conversion factors
10 dm 1m
1m dm

5. centi… is a smaller unit (c)
Means 1/100 or (10-2)
1 centimeter is .01meter (1/100 meter)
There are 100 cm in 1 m
2 Conversion factors:
100 cm 1m
1 m cm

6. milli… is a smaller unit (m)
Means 1/ or (10-3)
1 millimeter is .001meter
There are 1000 mm in 1 m
2 Conversion factors:
1000 mm m
1m mm

7. micro… is very small (μ)
Means 1/1,000,000 or (10-6)
1 micrometer (micron) is meter
There are 1,000,000 μ in 1 m
2 Conversion factors:
1x106 μ m
1m x106 μ

8. nano… very small (n) Means 1/1,000,000,000 or 0.000000001 (10-9)
1 nanometer is meter
There are 1,000,000,000 nm in 1 m
2 Conversion factors:
1x109 nm m
1m x109 nm

9. Converting between units: (dimensional analysis)
Know the definition of units
write the definitions
as conversion factors
Use the one that algebraically cancels the “given” unit
Solve the problem
Convert 3.5 mm to m:
1 m = 1x10 3 mm
1m 1 x 10 3mm
1 x 10 3mm m
3.5mm x 1m
1x10 3 mm
= 3.5x10 -3 m

10. Converting between units: try it yourself:
Convert 2.3x10 3 g to g:
(answer is: 2.3 x 10-6 g)
know the definition of units
write the definitions
as conversion factors
use the one that algebraically cancels the “given” unit
Solve the problem