Unit II.2: SI Units

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”

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

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

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

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.

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

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

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: ________

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

CONGRATULATIONS, NOW YOU KNOW SI UNITS!