Download Atomic mass

Atomic mass
mass of an atom
units:
amu or u (atomic mass unit)
Da (Dalton)
amu is expressed as the ratio of mass of an atom to that of
a chosen standard atom
today amu scale is based on an isotope of carbon,
12
C
amu is defined by assigning a mass of exactly 12 amu to
the 12C isotope of carbon
1 amu = 1 the mass of
12
12
C
Microscopic amounts - usually at the level of individual
atoms
Chemistry is done on the macroscopic level
Mole
-- SI unit for the amount of substance
-- Used to bridge the gap between the microscopic
and macroscopic levels of substances
-- invented to provide a simple way of reporting a
huge number of atoms and molecules in a visible
sample
1 mole = 6.0221367 x 1023 particles
= usually rounded to 6.022 x 1023 particles
= Avogadros’s number or Avogadros’ constant
particle = could be atom, molecule, formula unit or ion
spreading 6.022 x 1023 marbles over the entire surface of
the Earth would produce a layer of 3 miles thick
1 mole has a mass in grams numerically equal to the
atomic mass in amu
12.01 amu = mass of one atom of C
1.01 amu = mass of one atom of H
12.01 g = mass of one mole of C
1.01 g = mass of one mole of H
12.01 g
= mass of one mole of C
= 6.022 x 1023 atoms of C
= molar mass of C
= mass of one mole of C
12.01 amu
= mass of one atom of C
= atomic mass of C
1.01 g
= mass of one mole of H
= 6.022 x 1023 atoms of H
= molar mass of H
= mass of one mole of H
1 mole of atoms of any element = 6.022 x 1023 atoms