The Periodic Table

The Periodic Table is a way of listing chemical elements, substances that are made from one type of atom. Elements set the foundation for matter. Some examples of elements include, but are not limited to are oxygen, helium, gold, and silver. The Periodic Table is “periodic” because the elements are organized in rows and periods.

Each element has an atomic number. This number comes from the number of protons in each atom of the element. If you look a Periodic Table, you can see that the table arranges the elements in both rows and columns. From left to right, the elements are arranged in rows based on their atomic numbers. Each row is called in period, with the first having 2 elements, hydrogen and helium.

The columns form groups of elements that have similar properties. For instance, the 1st column containing lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), and Cesium (Cs), and Francium (Fr) make up alkali metals, metals that react with water and oxygen very quickly. The 2nd column of elements make up alkaline earth metals, and these metals are harder than and react slower to oxygen and water, than compared to alkali metals in Column 1. The grouping of similar elements allows chemists to easily work with elements by helping them predict how an element will react in an experiment.

There are currently 118 elements on the Periodic Table. Each element has its own abbreviation and name on the periodic table. Let’s take a look at Nitrogen.

On the top left, we can see that Nitrogen has an atomic number of 7. “N” is Nitrogen’s chemical symbol. 14.0067 is Nitrogen’s atomic mass, which is the sum of the protons and the neutrons.

The Periodic Table was created by Dmitri Mendeleev, a Russian chemist, in 1869. During this time, scientists didn’t know what atomic numbers were, only knowing an element had an atomic mass. Mendeleev realized that atomic masses correlated with properties of elements When he arranged the elements according to their atomic mass, it seemed as if the elements clustered in groups with similar properties.

The very first Periodic Table does not resemble the one we see today. As scientists after Mendeleev found new elements, the Periodic Table changed over and over again. Maybe the Periodic Table will just never stop changing.

Periodic Table

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