Relative atomic mass

• Relative atomic mass is the mean mass of an element compared to a carbon‐12 atom
• The relative atomic mass of carbon‐12 is exactly 12.0 so if an element as less than carbon-12 then it is under 12.0 and if it has more then it is over 12.0
• The periodic table shows the relative atomic mass of the elements. The bottom number in the periodic table box is the aromic mass of that element
• A chemical formula tells you how many atoms of each element there is in a unit of a substance. An example of this is H²O. This shows that hydrogen contains 2 atoms for each oxygen 1.