# timeline of periodic table

Timeline created by toddyp
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## The periodic table begins Johaan Dobereiner

Johaan Dobereiner grouped elements based on atomic weight.
Ca Sr Ba (40 + 137) ÷ 2 = 88
40 88 137
he noticed strotium fell exactly in the middle of calcium and barium.
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## Alexandre Beguyer de Chancourtois

Alexandre , was the first to understand the physical properties of elements. in 1862 he published a list of all the known elements at the time. the list was a helical graph wrapped around a cylinder . elements with similar properties occupied positions on the same vertical line of cylinder .
• # The law of the triads

Johaan Dobereiner explained the law of the triads to other scientists who built on Dobereiner's ideas .
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## Dimitri Mendeleev's periodic table

Mendeleev's periodic table of 1869 contained 17 columns with two partial periods of seven elements each followed by two nearly complete periods . The table contained gaps but Mendeleev predicted the discovery of new elements.
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## Law of octaves John Newlands

John Newlands was an english chemist. he noted down all 62 elements in order of atomic weights . he notice that after every 8 properties reapered. he was the first to notice the periocity of the elements .
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## Noble gasses william ramsey , lord rayleigh .

ramsey (chemist) + rayleigh (physist) were the first to dicover inert gasses . As this was a new dicovery they found that the periodic table didnt have these gasses so they positioned them into the correct groups .
• # the law of octaves

John Newlands wrote a paper on the law of octaves .

• # mandeleev revises the periodic table

In 1871 Mendeleev revised the 17-group table with eight columns (the eighth group consisted of transition elements). This table exhibited similarities not only in small units such as the triads, but showed similarities in an entire network of vertical, horizontal, and diagonal relationships.
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## Henry Moseley

henry moseley subjected known elements to x-rays. He was able topick out the relationship between x-ray frequency and number of protons. he then arranged the elements in order of atomic number not mass. this cleared the incosistancy of mendeleev's periodic table.
• # discorvery of Argon

rayleigh discovered the very unreactive gas argon.
• # Noble prizes

Rayleigh (physics) and Ramsey (chemistry) were awarded Nobel prizes in 1904
• # The nobel prize

In 1906, Mendeleev came within one vote of receiving the Nobel Prize in chemistry
• # discovery of the proton.

this discovery helped moseley with his input of the periodic table.
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## glenn seaborg modern table

seaborg's discovery of the transuranium elements was the finalising piece to the puzzle for the periodic table , this final discovery gave the table the widely know shape that it holds today.
• # Nobel prize

In 1951 Seaborg was awarded the Nobel Prize in chemistry and element 106 was later named seaborgium (Sg) in his honor.