Tutorial†† -†††† amu Ė atomic mass unit

 

To help you understand amu:

Letís use the sodium atom (Na) as an example.The number on the periodic chart for Na is22.99.†† ††Up to now, we have used this number for the mass of one mole of sodium.†† The amu is different because amu refers to atoms instead of moles.So, here is what it looks like:

 

††††††††††††††††††††††† 1 gram molecular wt Na (1 mole)†† =††† 22.99 grams(find this number on the Periodic Chart)

††††††††††††††††††††††† 1 atom of Na†† †††††††††††††††††††††††††††††††=††† 22.99 amuís

 

These two things (gram molecular wt and amu) are connected by Avogadro

 

††††††††††† 6.02 x 1023 atoms = 1 mole = 1 gram molecular weight

 

††††††††††††††††††††††††††††††††††††††††††††††† ††††† †††††††††††1 gram molecular weight

††††††††††††††††††††††† 1 atomís mass (amu)= ††--------------------------

††††††††††††††††††††††††††††††††††††††††††††††† ††† ††††††††††††††††††6.02 x 1023 atoms