Warmup How would a standard system of

measurements, agreed to and used around the world, make life easier? Give examples.

2.4 –MEASUREMENT AND SAFETY

Objectives:

1. Explain the importance of the International System of Units.

2. Determine the appropriate units to use for particular measurements.

3. Identify lab safety symbols, and determine what they mean.

Making Measurements The International System of Units (SI)

current name for the metric system.○ Used by most scientists and almost all countries.

All SI units are based on the number 10. Length

SI unit - meter (m).

Mass Amount of matter that something is made ofSI unit - kilogram (kg)

Volume Amount of space that something occupiesLiquids - liters (L) or milliliters (mL)Solids - cubic meters (m3), cubic centimeters (cm3)

DensityAmount of matter in a given volumeSI unit – gram per milliliter (g/mL) or grams per cubic

centimeter (g/cm3).

○ Derived quantity!

Temperature measure of how hot (or cold) something is.

○ Scientists often use degrees Celsius (°C) as the unit.○ SI base unit - Kelvins (K)

d e n s ity = m as s

v o lu m e

Areameasure of how much surface an object has Formula for area of a square or a rectangle:

Safety RulesAlways follow your

teacher’s instructions.Read lab procedures

carefully and thoroughly.Pay special attention to

safety information and know the safety symbols.