Chemistry 2.2 Development of the periodic table Flashcards
1
Q
How were elements ordered in the periodic table before?
A
atomic weight
2
Q
What happened if the order of atomic weights is followed?
A
It was incomplete and some elements were placed in innapropriate groups
3
Q
What did Mandaleev do to overcome some of these problems?
A
Left gaps for elements he thought had not been discovered and in some places changed the order based on atomic weights.
4
Q
What happened to the gaps Mandaleev left?
A
They were filled with elements with properties predicted by Mandaleev after discovered.
5
Q
Why did the knowledge of isotopes help?
A
Helped explain why the order based on atomic weights was not always correct
