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

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, kPamm of Hgatmosphere, atm.

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 1000m

1000m 1km

deci… is a smaller unit (d)

Means 1/10 or 0.1 (10-1)

1 decimeter is .1meter

There are 10 decimeters in 1 meter

2 Conversion factors

10 dm 1m

1m 10 dm

centi… is a smaller unit (c)

Means 1/100 or 0.01 (10-2)

1 centimeter is .01meter (1/100 meter) There are 100 cm in 1 m

2 Conversion factors: 100 cm 1m

1 m 100 cm

milli… is a smaller unit (m)

Means 1/1000 or 0.001 (10-3)

1 millimeter is .001meter

There are 1000 mm in 1 m 2 Conversion factors:

1000 mm 1 m

1m 1000 mm

micro… is very small (μ)

Means 1/1,000,000 or 0.000001 (10-6)

1 micrometer (micron) is .000001 meter

There are 1,000,000 μ in 1 m

2 Conversion factors:

1x106 μ 1m

1m 1x106 μ

nano… very small (n)

Means 1/1,000,000,000 or 0.000000001 (10-9)1 nanometer is .000000001 meterThere are 1,000,000,000 nm in 1 m

2 Conversion factors:1x109 nm 1m

1m 1x109 nm

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 3mm1 x 10 3mm 1 m

3.5mm x 1m 1x10 3 mm

= 3.5x10 -3 m

Converting between units: try it yourself:

know the definition of units

write the definitions

as conversion factors use the one that

algebraically cancels the “given” unit

Solve the problem

Convert 2.3x10 3 g to g:

(answer is: 2.3 x 10-6 g)