C2.1 - History Of The Periodic Table (Finished) Flashcards
How did John Dalton arrange the elements?
In order of their atomic mass
How did John Newland build on Dalton’s model?
He noticed thatcher properties of every eighth elements seemed similar so he arranged the elements in groups of eight.
What was the main problem with Newland’s table?
He assumed all the elements had been found so he filled his octaves without leaving gaps, even though some of the elements were not similar at all.
What was it that made mendleev’s periodic table accepted?
He arranged the elements in order of atomic mass, in octaves, but left out spaces for undiscovered elements. He later used the table to predict the properties of the undiscovered elements and when elements that fit and matched his predictions were found, the table was accepted.
Why is the periodic table of elements named periodic?
Because of the regularly recurring patterns in the elements’ properties. Also it is arranged into rows called periods
Mendeleev had to move some elements in his table out of order of mass too make the octaves work. How was this problem eventually solved?
In the 20th century when scientists found out more about the structure of atoms, they arranged the elements in order of number of protons.
Who made the first (main) suggestion on how to arrange the elements?
John Dalton
What did John Newland call the pattern of the elements where every 8th element would have similar properties to the previous 8th?
The law of octaves
What did old scientists have to go by to categorise elements? (2 things)
1j Their physical and chemical properties
2) Their relative atomic mass
