Chapter 2.1 Development of the periodic table Flashcards
Why did Mendeleev’s periodic table have gaps?
Mendeleev left the gaps for unknown elements, which when discovered matched his predictions.
Why did other scientists disagree with Newlands?
John Newlands put forward his law of octaves in 1864 in which he arranged all the elements known at the time into a table in order of relative atomic mass. When he did this, he found that each element was similar to the element eight places further.
How did Mendeleev persuade doubters that his periodic table was a useful tool in understanding chemical elements?
He arranged the table in a pattern so that the element properties could be seen but also left gaps for elements that had not yet been discovered. A few years later, these unknown elements were discovered with properties that closely matched his predictions.
