The Modern Periodic Table

The Modern Periodic Table

1. Atomic number: the number of protons in its atom

   • Mass number: the total number of protons and neutrons in the atom

2. In chemical symbols, the number on the top is the atoms mass number, and at the bottom is the atomic number (protons)

   • This can be used to calculate the number of protons, neutrons and electrons
     • For example Aluminium has an mass number of 27 (top) and a atomic number of 13 (bottom), so this means Al has 13 protons and 14 neutrons, it also will have 13 electrons orbiting the nucleus on the inner and outer shells
       • The groups in the periodic table are labelled 1-7 with the end group being 0 (noble gasses)

3. Relative atomic mass

   • The mass of an atom so small we can't use kg's to measure it. Instead we use the symbol for relative atomic mass as 'Ar' (small r) and other elements are compared to that of Carbon because it is know as a 'standard atom' (6,6,6:p,e,n)

4. The elements in the modern periodic table are in order of increasing atomic number

   • It also has horizontal rows called periods and the vertical columns are called groups
     • Each group has elements which contain similar properties

5. Isotopes (H):

   • versions of the same element with the same number of protons and electrons but have a different number of neutrons
     • Different mass number, same proton number