The Early Periodic Table 2

The work of John Newland in 1864

Newlands recognised that 8th seemed to be very similar to the 1st of the previous 7 when laid out in a 'periodic' manner and he was one of the first scientist to derive a 'Periodic Table' from the available knowledge. Although none of his vertical column groups match completely but the basic pattern of the modern periodic table was emerging. However column's 1 and 7 do seem to be particularly mixed up compared to the modern periodic table!

Dmitri Mendeleev's Periodic Table of 1869

Mendeleev laid out all the known elements in order of 'atomic weight' (what we now call relative atomic mass) except for several examples like tellurium (Te) and iodine (I) whose order he reversed because chemically they seemed to be in the wrong vertical column! He arranged similar elements into vertical columns (we now call groups) and switched to the next row (we now call periods) when the next similar element appeared when laid out in atomic number (left to right and then down). He wrote out all the known properties of at least 50 elements and looked for deeper and more meaningful patterns than his predecessors like Newland. He recognised that even more elements could be fitted into groups of elements with similar properties, and these he arranged as vertical columns, which we now call groups (of the periodic table).