Creating the Periodic Table

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The periodic table is often the first thing that comes to mind for many people when thinking about chemistry. Many of us have seen it as early as grade school and it's a great reference for learning more about the different elements. Did you know that only 15 elements were known in the 1700s? As the number increased, many people attempted to find a way to organize them. Today's free Chemistry video is about the history of the periodic table and how it evolved into the useful tool it hanging in all chemistry classes.

It wasn't until Dmitri Mendeleev took a stab at it that what we know as the Periodic table began to evolve.  He saw that it would be possible to arrange the elements in order of atomic weight and chemical reactivity. Based upon his new organization, Mendeleev noticed some missing spaces and using the chart was able to make predictions about undiscovered elements that turned out to be very close to reality. As scientists began discovering more elements, they encountered new issues that instigated further changes to the order of the table. These discoveries caused scientists to realize that atomic number, or the number of protons in an atom, is a better criterion than atomic weight in ordering the elements. It was this realization that resulted in the table we know today.


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This page contains a single entry by April Stockwell published on April 20, 2011 2:02 PM.

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