In 1789, Antoine Lavoisier published a list of 33 chemical elements.
Lavoisier grouped the elements into gases , metals , non-metals , and earths .
Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads (groups of three) based on their chemical properties. Lithium , sodium , and potassium , for example, were grouped together as being soft, reactive metals.
Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third. Same is true for other properties like Density. These groups were known as Döbereiner’s triads .
John Alexander Reina Newlands published a series of papers in 1864 and 1865 that described his attempt at classifying the elements: When listed in order of increasing atomic weight, similar physical and chemical properties recurred at intervals of eight , which he likened to the octaves of music .
Dmitri Ivanovich Mendeleev and Julius Lothar Meyer independently published their periodic tables in 1869 and 1870, respectively.
They both constructed their tables in a similar manner, by listing the elements in a row or column in order of atomic weight and starting a new row or column when the characteristics of the elements began to repeat.
With the development of theories of atomic structure , it became apparent that Mendeleev had inadvertently listed the elements in order of increasing atomic number .
The modern version of the periodic table was based on the Periodic Law, which states that when elements are arranged in an increasing atomic number, their physical and chemical properties show periodic pattern.