SI units

SI units (Système international d'unités) are now the general fundamental units for scientific work. They are based on seven base units for seven base quantities which we assume to be mutually independent. The main basic units with which you will be concerned are the meter (m), the kilogram (kg) and the second (s). Other non-SI units, notably minute (min), hour (h), degree Celsius (°C) and litre (l) are still commonly used in science.

The Seven Base Units are as Follows:

Base Quantity                              Name                 Symbol

Length                                          meter                       m

Time                                             second                    s

Mass                                            kilogram                  kg

Amount of Substance                     mole                       mol

Thermodynamic Temperature          kelvin                       K

Electric Current                              ampere                    A

Luminous Intensity                         candela                    cd

When using abbreviations, never add the letter "s" in an attempt to signify plurals. Below are some of the common symbols:

Symbol	Prefix	Factor
c	centi	10-2
m	milli	10-3
μ	micro	10-6
n	nano	10-9
p	pico	10-12

(1 l = 10³ ml = 10⁶ μl, 1g = 10³ mg = 10⁶ μg)