📊 RELATIVE ATOMIC MASS
PAGE 1 OF 5, NOT WHOLE NUMBERS
TEAM WEIGHT
WHY Ar IS NOT AN INTEGER
Look at chlorine on the periodic table and you will not see a neat whole number. Relative atomic mass, Ar, is a weighted average of the masses of an element's naturally occurring isotopes. Chlorine is mostly chlorine-35 with some chlorine-37, so the average sits near 35.5.
📊 Ar
Relative atomic mass is the average mass of atoms of an element compared with one twelfth of the mass of a carbon-12 atom.
AVERAGE!
ISOTOPES
⚛️ Same protons, different neutrons
⚖️ Different masses for one element
🌍 Nature mixes them in fixed ratios
⚖️ Different masses for one element
🌍 Nature mixes them in fixed ratios
THE TABLE
📋 Periodic table lists Ar values
🔢 Often not whole numbers
🧪 Chemists use Ar for mole maths
🔢 Often not whole numbers
🧪 Chemists use Ar for mole maths