The History of the Periodic Table - Law of Octaves

In 1864, a British scientist called John Newlands came up with the idea of arranging elements in order of their atomic mass. This was known as the Law of Octaves. He did this by arranging them into columns in order of relative atomic mass (this is the mass of the protons + the mass of the neutrons).





Newlands placed the elements into eight columns, as he discovered that every eighth element had similar properties, so in theory, the elements in a particular row should all have the same properties. 


However, due to the fact that not all of the elements are in the table, this wasn't entirely accurate as gaps weren't left for the missing elements, so some elements were placed with others that had completely different properties. For example, Iron (Fe) has been placed in the same row as two non-metals, Oxygen (O) and Sulphur (S) which have completely different properties to metals. For this reason, other chemists didn't use it.


Also, another way in which this was incorrect is that some elements are shown to have the same atomic number. This is incorrect due to the fact that no two elements have the same relative atomic mass, as this is a unique number that determines what element an atom is and it is impossible for one atom to be two different elements.