History Of The Periodic Table Flashcards
1
Q
Johann Dobereiner
A
Groups of 3 elements
Appearance and reactions are similar
RAM of middle element is close to other 2 elements in the triad
Atomic mass important when grouping
2
Q
John newlands
A
Order of atomic mass
Each element had similar properties to an element 8 places along
Properties kept repeating
Problems
Oxygen and iron in same group
3
Q
Dmitri Mendeleev
A
Arranged in order of atomic mass
Gaps for undiscovered elements
Broke his rules and switched tellurium and iodine because they had similar properties to eachothers groups
4
Q
Henry Moseley
A
Elements need grouping by atomic number(number of protons)
Used atomic mass to help group elements
