Editing Atomic mass units

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{{numeric}}
The Atomic Mass Unit is defined as the twelfth part
The '''atomic mass unit''' (AMU) is defined as the twelfth part
of the mass of a C<math>_{12}</math> atom.
of the mass of a C<math>_{12}</math> atom.
Its value (in SI units,
This is <math>1.66054\times10^{-27} </math> kilograms
[http://physics.nist.gov/cgi-bin/cuu/Value?tukg|search_for=atomic+mass+unit CODATA] value) is
in SI units.
:<math>1.66054\times10^{-27} </math> kilograms
 
Hence,
Hence,
it is approximately equal to the mass of a proton.
it is approximately equal to the mass of a proton.
Elements are assigned masses in these units which are
Elements are asigned masses in these units which are
not integer numbers. This is because
not integer numbers. This is because
neutrons and protons have slightly different masses,
neutrons and protons have slightly different masses,
because nuclear binding forces cause the total mass
because nuclear binding forces cause the total mass
of a nucleus to be less than that of the sum of
of a nucleum to be less than that of the sum of
its constituents, and, mainly, because of the
its constituents, and, mainly, because of the
appearance of natural isotopes. Thus, Potassium
appearance of natural isotopes. Thus, Potassium
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isotopes.
isotopes.


Here is a list of masses of elements and compounds in atomic mass units:
Here is a list of masses of elements and compounds in amus:
{| border="1"
{| border="1"
|-  
|-  
| Compound/element || mass in amu
| Compound/element || mass in amu
|-  
|-  
| Ar ([[argon]])|| 39.948
| Ar || 39.95
|-
| C || 12.0107
|-
| =CH || 13.01864
|-
| -CH<sub>2</sub>- || 14.02658
|-
| -CH<sub>3</sub> || 15.03452
|-
| Xe || 131.293
|-  
|-  
| CO<sub>2</sub> ([[carbon dioxide]])|| 44.0095
| Xe || 131.29
|-  
|-  
| H || 1.00794
| CO2 || 44.01
|-  
|-  
| H<sub>2</sub>O ([[water]]) || 18.02
| H2O, water || 18.02
|-  
|-  
| N<sub>2</sub> ([[nitrogen]])|| 28.01
| N2 || 28.01
|}
|}
Note that sometimes the atomic mass unit is also known as the '''Dalton''' ('''Da'''), especially when dealing with macromolecules such as  [[proteins]].
==References==
#[http://www.iupac.org/reports/periodic_table/index.html IUPAC Periodic Table]
[[Category: Physical constants]]
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