# Chemistry

Learning physics and chemistry easily and freely - Science for elementary school, middle school and high school

Free online chemistry lesson for elementary school, middle school and high school.

## Mass and its units

1) What is mass ?

The mass of an object reflects the amount of matter it contains:
The mass increases with the amount of matter.

The mass also depends on the type of material that an object is made of.

Mass and weight are often confused whereas they are different.

2) Mass units

According to the insternational system the standard mass unit is the kilogram whose symbol is kg but it is also possible to use multiples and submultiples of the gram:
- The hectogram (hg)
- The decagram (dag)
- The gram (g)
- The decigram (dg)
- The centigram (cg)
- The milligram (mg)

Other units of masses can also sometimes be used:
- The tonne (t): a ton is 1000 kg
- The quintal (q): a quintal is 100 kg

The transition from a unit mass to another can be done with the following conversion table:

 kg hg dag g dg cg mg

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