The Genius Of Mendeleev's Table - Let's Talk Science

In 1869, a Siberian chemist named Dmitri Mendeleev invented the Periodic Table of Elements. Many of us know it simply as the periodic table. You have probably seen the periodic table before. It may even be hanging on the wall of your chemistry class.

What is the periodic table?

The Periodic Table of Elements is an arrangement of the chemical elements in table form. The table is arranged into seven periods and 18 groups. The rows are called periods, and the columns are called groups.

In the table, elements are arranged based on their atomic number, electron configurations, and chemical properties. You can also use the table to quickly find an element’s symbol and atomic mass. Elements on the left-hand side of the periodic table are generally metals. Elements on the right-hand side are generally non-metals.

What is so special about Mendeleev’s table?

Mendeleev was not the first person to try to organize the elements. Other scientists had listed the elements. Some of these scientists had even grouped elements with similar properties together. So why was Mendeleev’s idea the one that lasted?

Unlike those other scientists, Mendeleev predicted that there would be more chemical elements to come. And he was right! Today, the periodic table has 118 elements. But in Mendeleev’s time, scientists only knew of 63 elements.

When Mendeleev devised the periodic table, he left plenty of blank spaces and dashes. For example, he set aside a place for eka-aluminum. This place was one step away from aluminum. No one had discovered this element yet. But Mendeleev was able to predict many of its properties based on the properties of the elements surrounding it.

Sure enough, a few years later, the French chemist Paul-Émile Lecoq de Boisbaudran discovered gallium. Look at your periodic table. Where is gallium? That’s right, one step away from aluminum! And it turned out that Mendeleev’s predictions about the properties of this element were spot-on! He also predicted the existence of at least 5 other elements. He even predicted a very rare element called technetium!

Did you know?

Long after his death, Dmitri Mendeleev had an element named after him: Mendelevium, atomic number 101.