1863: British chemist John Newlands organizes the known elements, listing them in a table determined by atomic weight, according to what he provisionally calls his "law of octaves." It is not an instant hit.

Newlands noticed, as he cataloged the elements sequentially based on Stanislao Cannizzaro's atomic-weight system, that elements with similar properties tended to appear in intervals of eight, reminding him of the perfect eighth, or octave, in music. He called his explanatory paper "The Law of Octaves, and the Causes of Numerical Relations Among the Atomic Weights."

He arranged the elements both in order of succession (like Cannizzaro) and in such a way as to get elements with similar characteristics on the same line of his table. This required some fudging on Newlands' part and ultimately resulted in some inaccuracies.

Nevertheless, Newlands defended his org chart, saying that no other method for cataloging the elements was workable.

Newlands' table was initially dismissed by the English Chemical Society as irrelevant. It wasn't until the Russian chemist Dmitri Mendeleev published his own periodic table of the elements in 1869 that Newlands' achievement began to be appreciated. Still, it would be another 18 years before the Royal Society got around to awarding Newlands the Davy Medal in recognition of his work.

And it wasn't until 1913 that Henry Moseley established that the properties of the elements varied periodically according to atomic number, not atomic weight.

(Source: Various)