Mendeleev´s Periodic Table Flashcards

All 4 cards in this deck

How did Mendeleev arrange the elements in his periodic table?

In order of increasing relative atomic mass, grouping together elements with similar properties of the elements and their compounds.

Why did Mendeleev leave gaps in his periodic table?

For elements that had not yet been discovered, so that the known elements lined up with others of similar properties.

How did Mendeleev predict the properties of elements that had not yet been discovered?

He used the trend/pattern in the elements around the gap (above and below in the same group, left and right in the period), taking a value between the surrounding elements.

Why was Mendeleev's ordering by increasing relative atomic mass not always true?

Because of the relative abundance of the isotopes of some elements: in a few pairs, such as tellurium and iodine, the element that belongs first has the higher relative atomic mass.