Scientific Measurement Wilbraham, Antony C., Dennis D. Staley, Michael S. Matta, and Edward L. Waterman. Prentice Hall Chemistry. 1st ed. Upper Saddle River, NJ: Pearson Prentice Hall, 2008.

International System of Units (SI) SI units is a revised version of the metric system.  The metric system is based on units of 10.  From the 7 base units all other measurements can be derived.  SI units used by Chemist  Meter (m), gram (g), Kelvin (K), and second (s)

SI Base Units used by chemists: The meter (m) is used to measure length. The gram (g) is used to measure mass. The Kelvin (K) is used to measure temperature. The second (s) is used to measure time. The Liter (L) is used to measure volume

Tro, Chemistry: A Molecular Approach 4Volume Derived SI unit ◦ any length unit cubed Measure of the amount of space occupied SI unit = cubic meter (m 3 ) Commonly measure solid volume in cubic centimeters (cm 3 ) Commonly measure liquid or gas volume in milliliters (mL)

Water displacement What is the volume of the fish?

Density Ratio of mass to volume. Units are g/cm 3 or g/mL. All pure substances have a known density. Example: Density of water is 1.0 g/mL and the Density of zinc is g/cm 3 Density of solids is greater than that of liquids. Gases are the least dense. ◦ except ice is less dense than liquid water!

METRIC PREFIXES Metric PrefixesSymbol Kilo-k Hecto-h Deka-da Base Unit (meter, gram, sec, Kelvin) Deci-d Centi-c Milli-m

Examples: ◦ You can add a prefix to any base unit: EXAMPLES: ◦ Milligram ◦ Centimeter ◦ Kilogram

Dimensional Analysis Practice

Multi-Step Dimensional Analysis Problems: (Copy and Skip 5 lines in between each problem) 1. ) A pumpkin has a mass of 100 pounds. How many milligrams is this? (Given: 1 pound = 454 grams) 2.) Dracula drank 987 quarts of blood. How many milliliters is this? (Given: 1 L = qts) 3.) The scarecrow is 67.9 inches tall. How many meters is this?(Given: 1 inch = 2.54 cm)