Science loves units. But then again, they are a necessity. If you are going to measure something, you will need a way to tell people how much you have. Here are only a few we use in Chemistry...

PERCENTAGES
When you need to know how much of something you have compared to a whole. It is figured out by taking a decimal number and multiplying by 100.
"I have 20% of what I started with." That means you lost 80%.

GRAMS, KILOGRAMS, MILLIGRAMS
These are measures of mass.
"This candy bar has a mass of only a few grams."

LITERS, MILLILITERS
These are measures of volume.
"I just bought a 2 liter bottle of soda."

DEGREES CELSIUS, DEGREES FAHRENHEIT, AND KELVIN
These are different measurements scientists use for temperatures.
"It's freezing outside." That could mean it is 0^oC, 32^oF, or 273K (just Kelvins, no degrees).

ATOMIC MASS UNITS
The way to measure the mass of different atoms.
"Carbon-12 weighs 12 AMU."

CALORIES
A unit of energy.
"A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius."

JOULES
It is a unit of energy.
"4.8 Joules is the same as 1 Calorie."

SECONDS, MINUTES, HOURS
Measures of time.
"There are 60 seconds in a minute and 60 minutes in an hour."