Medeleev's table Flashcards
How did Mendeleev put the elements in order?
By checking the properties of elements and compounds.
Did Mendeleev swap some elements so that elements with similar properties lined up?
Yes (pair reversals)
What did Mendeleev put the element in order of?
The relative atomic masses.
How did Mendeleev predict other elements?
By leaving gaps in the table, and predicted those element’s properties.
Were Mendeleev’s predictions right when the elements he predicted were discovered?
Yes, they fitted the properties very well.
When did Mendeleev arrange his table, and when was the second one published?
1869, and 1871.
Had Mendeleev arranged the elements by relative atomic mass successfully?
No, there were some pair reversals, like where Mendeleev swapped elements like tellurium and iodine to make the properties match.
He didn’t know it at the time, but he had actually arranged them by atomic number, so he was correct.
Describe how Mendeleev arranged the elements known to him.
In order of increasing (relative) atomic mass, taking into account the properties of the elements and their compounds.
What did Mendeleev find out?
That the physical and chemical properties of elements were related to their (relative) atomic mass.
He also found out that the properties of each element repeated every 8th element (groups).
How did Mendeleev list them?
So that groups of elements with similar properties fell into vertical columns.
Do group 7 elements react with water?
Yes
Do group 7 elements react with oxygen?
No
Mendeleev published another table in 1871. Mendeleev left gaps in his table.
Explain the importance of doing this.
The gaps were for elements not discovered then. Mendeleev used his table to predict the properties of these elements. When they were discovered later, their properties closely matched his predictions. This supported the ideas behind his table.
Suggest one reason why other scientists at the time thought that Mendeleev’s table was not correct.
It had gaps/there were pair reversals/some groups contained metals and non-metals.
Approx. how many elements did Mendeleev have to work with?
40-50
