Chemistry
You will get to learn about the history of the Periodic Table and how the elements are arranged. Learn to easily locate metals, nonmetals and metalloids on the table and learn how atomic mass is calculated.
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After completing this tutorial, you will be able to complete the following:
Who first developed the Triads Rule and what is it?
~ The Triads Rule was first developed by chemist Johann Döbereiner in 1826. The Triads Rule grouped elements in threes according to their atomic weights. Döbereiner discovered that the atomic mass of an element in the middle was close to the average of the atomic masses of the elements on either side.
Who first developed the Law of Octaves and what is it?
~ The Law of Octaves was developed by British chemist John Newlands in 1864. Newlands noticed that when the elements were arranged according to their increasing atomic weights, one element had the same properties as the eighth element following it. Because he related this idea to the notes in a musical scale, he called it the Law of Octaves.
Who designed the first draft of the Periodic Table and what did it look like?
~ In 1869, Dmitri Mendeleev drafted the first Periodic Table. He arranged the elements side by side according to their atomic weights, but began a new line when he found elements with similar characteristics. This resulted in columns of elements with similar characteristics. Elements were also arranged by their atomic numbers, but at the time Mendeleev did not realize that he had done this.
Why did Mendeleev leave blank spaces in his Periodic Table?
~ Mendeleev knew there were elements that had yet to be discovered and wanted to leave room for them on the table.
| Approximate Time | 2 Minutes |
| Pre-requisite Concepts | Students should have general understanding of the law of octaves and the law of triads. |
| Course | Chemistry |
| Type of Tutorial | Animation |
| Key Vocabulary | law of octaves, law of triads, |
