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Dobereiner
In 1817, Dobereiner noticed two things about the 3 elements calcium, strontium and barium. He noticed:
1.That they have similar properties.
2.That they have a similar atomic mass. -
Law Of Triads
Dobereiner created a 'law of triads' this law stated that the atomic mass of the middle element was the arithmetic mean of the other two elements. -
How many elements were discovered by 1860?
62 elements had been discovered by 1860. -
John Newlands 'Law of Octaves'
In 1865 ,John Newlands created his law of octaves. He arranged the 62 elements in increasing order of their atomic weights. He discovered that every 8th element displaid similar characteristics. -
Dimitri Mendeleev
Mendeleev was responsible for creating the first periodic table of elements in 1869. To help him create the periodic table, he wrote down all the elements with their key properties on cards. He arranged them in different ways such as; arranging the elements in asscending order by atomic weight, laying out the elements in certain patterns and grouping the elements in vertical columns. -
Moseley
Moseley was an english scientist who sorted out the real pattern and got rid of any problems and inconsistencies, made by Mendeleev. He then arranged the elements by atomic number instead of atomic mass.
