The Periodic Table of Elements

On the Periodic Table of Elements, which element is represented by the letter K?

And the answer: potassium.    

Photo credit: public domain. 

On the periodic table, potassium is represented by the letter K, because its Neo-Latin name is kalium. Potassium is very important to plants and animals, as plants need it for photosynthesis, and it helps animal muscles work, including the muscles that control the heartbeat and breathing.

The periodic table is an exhibition of human genius. Dmitri Mendeleev, a Russian-born scientist of the 1800s, invented not just a means of organizing the Earth's elements, but created a template that would go so far as to predict those which had not yet been discovered.

During his studies of chemistry, Mendeleev worked as a student in major laboratories, working with every element he could get his hands on. With this hands-on knowledge of the field, he then looked to categorization. At the time the 60 known elements were sorted according to atomic weight. However, Mendeleev soon realized that the most significant relationships between elements had little to do with their respective atomic weights: the relationship between weights was periodic.

At the beginning of the list of elements, characteristics repeat every seven elements (it was later determined that they repeat every eight elements, but in the 1860s the noble gases had not yet been discovered). As the masses of the elements increased, the pattern of repetition continued, but, as Mendeleev discovered, the pattern began to get fuzzier the farther down on the table he went.

This puzzled the scientist. How could he make sense of deviations from a pattern if half of it fit perfectly? Then, a realization: the numbers weren't working not because the ideas were wrong, but because some elements simply hadn't yet been discovered.

As such, Mendeleev inserted gaps into the periodic table, and the elements fell perfectly into place. Seven element periods for the first two rows, and 18 element periods for the next two. Mendeleev was so certain that he went so far as to predict the properties of the missing elements!

Since his discovery, the periodic table has made its way into nearly every chemistry lab in the world. Learn more about the groupings and usage of the periodic table here.

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