1. Unit II.2: SI Units

2. What are SI Units?
The International System (SI) of metric units has numerous “base units”. Base Units are basic units of measurement.
Ex)
metre “m” gram “g”
second “s” mole “mol”

3. REMEMBER THIS! Some important equivalences used in chemistry are :
1 mL = 10 m³ m³ = 10 L³ t = 10³ kg
REMEMBER THIS!

4. Quiz Time!! Try to answer these 3 questions : 10 t = ____ kg
50 mL = ____ cm³ ____ m³ = 100³ L
10 t = ____ kg

5. If you answered : 10 t = 10⁴ kg 50 mL = 50 cm³ 10 m³ = 100³ L
Then you are CORRECT!!!

6. PREFIX AND UNIT SYMBOLS AND EXPONENTIAL EQUIVALENT
Prefix symbols are symbols that go before the base unit.
Ex) By adding the prefix “k” to a base unit “g” would make it “kg”
The Exponential Equivalent is the value of “k” which is 10³.

7. Re-writing 2.7 x 10⁻²
First, find the prefix equivalent to 2.7 x 10⁻², which is centi “c” because 10⁻² = “c”.
Then look for the base unit, which is “m”
Finally add the prefix and the base unit together, forming “cm”
Your final answer would be 2.7 centimeters!
Centimeters
Millimeters

8. Try This!
REWRITE the following using PREFIX and UNIT SYMBOLS and EXPONENTIAL EQUIVALENT:

9. A) 2.5 centimeters C) 2.5 millimetres
Prefix Symbol: ________ Prefix Symbol: ________
Unit Symbol: ________ Unit Symbol: ________
Exponential Exponent: ________ Exponential Exponent ________
B) 1.3 kilograms
Prefix Symbol: ________
Unit Symbol: ________
Exponential Exponent: ________

10. ANSWERS!!!! A) 2.5 centimeters C) 2.5 millimetres
Prefix Symbol: “c” or centi Prefix Symbol: “m” or milli
Unit Symbol: “m” or metre Unit Symbol: “m” or metre
Exponential Exponent: 10⁻² Exponential Exponent: 10⁻³
B) 1.3 kilograms
Prefix Symbol: “k” or kilo
Unit Symbol: “g” or gram
Exponential Exponent: 10³

11. CONGRATULATIONS, NOW YOU KNOW SI UNITS!