The Development of the Periodic Table Flashcards
What did scientists identify many years ago?
Elements as chemicals that couldn’t be broken down
What did some scientists try to do?
They tried to find patterns in these elements, other scientists didn’t think it was possible.
What did Dobereiner realise in 1817?
Some elements with similar properties formed groups of three.
What did he call these groups?
Triads
Give an example of this
Lithium, Sodium and Potassium or Chlorine, Bromine and Iodine
What did Newlands suggest in 1865?
That when elements were arranged in order of increasing atomic weight, some repeating patterns in properties could be seen.
What did he call this?
The Law of Octaves, after the musical scale
What did other scientists think of this?
They thought it was ridiculous
What did Mendeleev present in 1869?
He presented his periodic tables, which is much like the one we use today.
What did his table allow?
Similar elements to be grouper together and also showed the repeating patterns that other chemists has noticed.
Why did Mendeleev leave gaps in his periodic table?
For elements that he suggested hasn’t been discovered yet. He even correctly predicted the properties of these elements
What new technologies have been very important in discovering new elements?
ie. Spectroscopy helped discover the noble gases, which Mendeleev didn’t include in his periodic table because none of them has yet been found
