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12/8 - Dmitri Mendeleev's Periodic Table

Last updated over 3 years ago
9 questions
The periodic table of elements arranges all of the known chemical elements in grid-like chart. The modern periodic table organizes elements from left to right in order of increasing atomic number, which is the number of protons in each element’s nucleus. Depending on where an element is located on the table, many of its properties can be predicted, including mass, size, and chemical reactivity. However, the elements weren’t always organized in such a clear way. For many years, chemists looked for a logical way to organize the known elements. This became increasingly important as more and more elements were discovered. In 1869, an ingenious method of organizing elements was created by a Russian scientist named Dmitri Mendeleev.
1

How is the modern periodic table organized?

1

Who created the first successful periodic table?

1

In what year?

An Intense Card Game

Mendeleev was a fanatical card player and he used this talent in his task. He collected information about all of the known elements at the time and made a set of cards for them, similar to a deck of playing cards. On each card, Mendeleev wrote the element’s name, chemical symbol, atomic mass, and its physical and chemical properties. Mendeleev then arranged and rearranged the cards in countless different ways, looking for a relationships to their physical and chemical properties.
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What were 5 pieces of information that Mendeleev wrote on each element’s card?

Mendeleev began to notice a pattern when he arranged the elements in order of increasing atomic mass, but the pattern was not perfect. Mendeleev worked intensely on his “game” for three straight days, after which he went to sleep. According to Mendeleev, he has a vivid dream in which all of the elements fell into place. When he woke up, he immediately wrote the idea on a piece of paper, which only needed minor corrections as he perfected his theory. A sample of Mendeleev’s early periodic table follows on the next page.
1

Mendeleev began noticing patterns when he arranged the elements according to what?

Mendeleev’s New Periodic Table

From left to right across each row of his table, elements were arranged by increasing atomic mass. Mendeleev discovered that if he placed eight elements in each row and then continued on to a new row, the columns of the table would contain elements with similar properties. He called the columns groups, while rows were called periods. Mendeleev’s table of the elements is called a periodic table because periodic is a word that refers to anything that repeats.
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In Mendeleev’s new table, patterns in reactivity appeared to repeat after how many elements?

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In Mendeleev’s periodic table, rows were called _______ and columns were called _______ .
A Bold Prediction

The greatness of Mendeleev’s idea was that he left blank spaces for elements that had not yet been discovered. Not only did he leave spaces for these elements, but he predicted the properties of these elements based on their position in his table. The first of these elements fit into row 5 of group III in his table, which Mendeleev called eka-aluminum because it was one after aluminum (eka = 1 in Sanskrit). He predicted that the missing element would have an atomic mass of 68 and be a relatively soft metal like other elements in this group.
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Give 2 reasons why Mendeleev’s periodic table was so revolutionary at the time. What made it great?

Mendeleev’s Periodic Table Finally Accepted

An important measure of a good model is its ability to make accurate predictions. Indeed, Mendeleev’s periodic table could do this with great accuracy. At first, Mendeleev’s periodic table had few supporters. It gradually gained acceptance over two decades as 3 new elements that possessed the same properties as Mendeleev’s predictions were discovered (scandium, germanium and technetium). After 1889, Mendeleev’s periodic table was widely accepted. Although he never won a Nobel prize for his ideas, Mendeleev was honored after his death in 1955 when a manmade element with atomic number 101 was named Mendelevium after him.
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What were the 3 other elements that Mendeleev successfully predicted the existence of?