C3.1.1 The early periodic table Flashcards
Describe John Newlands’ octaves.
He arranged all the elements in a table in order of relative atomic mass.
In rows of 8, each element was similar to the element 8 places after it - columns / groups of similar elements.
What was the problem with Newlands’ octaves?
It did not work for elements past calcium.
It was ordered strictly by relative atomic mass so some elements were placed in the wrong groups.
Describe Mendeleev’s periodic table.
He arranged all the elements in a table in order of relative atomic mass.
Groups of elements with similar properties fell into vertical columns in his table.
Left gaps - thought elements had not yet been discovered.
What allowed Mendeleev’s to prove his table was correct?
He could predict the properties of the elements that he had left gaps for and these predictions were correct when they were later discovered.
