Discovering the Periodic Table Flashcards
How many elements were known in 1860?
60
What did people know about elements in 1860?
They knew lots of their properties but everything was scrambled.
Who is Dmitri Mendeleev?
He was a Russian chemist who sparked a turning point in chemistry.
What did Mendeleev do?
Mendeleev devised the periodic table.
What is the periodic table?
The periodic table is vital in chemistry. It shows us patterns in properties and helps us make predictions.
Who is Cannizzaro?, and what did Mendeleev have to do with him?
Cannizzaro held a conference in Germany, where he showed his results. He worked out the mass of the Atoms of the elements known at the time.
Mendeleev took a copy of his data.
What did Mendeleev do to devise the periodic table?
One day at home whilst writing a text book, Mendeleev wrote out some cards with all the information he knew about the elements and he tried to organize them.
What did Mendeleev put on the cards?
Atomic mass
Physical Properties
The formula of it’s compounds with Hydrogen and Oxygen
What order to Mendeleev put the cards in?
Atomic mas order.
The cards with similar properties were grouped together, he wrote his findings on the back of an envelope. This was the first periodic table.
What did Mendeleev leave gaps for?
He left gaps for unknown elements. Later these were found by chemists.
What were some of the missing elements?
Gallium, Scandium and Germanium.
What happened in 1925?
There were 2 unknown elements missing in the periodic table.
Who filled the 2 gaps in the periodic table?
Tacke and Noddack tried to by extracting ore.
What did Tacke and Noddack do?
They asked Otto Berg to test their substance. He confirmed it was a missing element. T and N called this Rhenium.
What is Rhenium?
It speeds up chemical reactions, it is a catalyst. It’s used in alloys for jet engine parts.
