Chemistry- Development of the periodic table (year 9) Flashcards
1
Q
What happened in the early 1800s?
A
elements were arranged by atomic weight
2
Q
How did they categorise elements?
A
by their physical and chemical properties and their atomic weight
3
Q
What happened with the early periodic tables?
A
they were not complete and some elements were placed in the wrong group and their properties were not taken into account
4
Q
What did Mendeleev do?
A
He left gaps and predicted new elements
5
Q
What happened with Mendeleev in 1869?
A
He overcome some of the problems with the periodic table by taking 50 known elements and arranging them into his own table
6
Q
Why did Mendeleev leave gaps in the table?
A
to make sure that elements with similar properties stayed in the same groups
