Today’s Wonder of the Day was inspired by Ryan from Delaware, OH. Ryan Wonders, “Why was the Periodic Table made?” Thanks for WONDERing with us, Ryan!
When you go out to eat at a restaurant, and you're sitting, waiting for your food to arrive, have you ever looked at your fork– we mean REALLY looked at it– and WONDERed what it's made of? Or when your food arrives, do you examine a sweet potato fry closely and try to see what makes it up?
Thanks to modern chemistry, it's much easier to know about what stuff is made of. Before today's scientific principles came about, ancient peoples had some interesting ideas about the stuff that composed the universe.
For example, the ancient Chinese and Greeks believed that the basic elements that existed in the world were things such as air, fire, water, earth, ether, wood, and metal. Today, we know all those things are made up of atoms of particular elements, such as oxygen, hydrogen, and carbon.
As elements were discovered and named, it became necessary to develop a system to organize all the elements. The system we know today as the periodic table of elements was conceived in 1869 by a Russian chemist named Dmitri Mendeleev. Although other chemists made contributions to the idea of a periodic table, like Julius Lothar Meyer, Alexandre Béguyer de Chancourtois, and John Newlands, most of the credit goes to Mendeleev.
Mendeleev organized the 64 elements known at that time in order of their atomic weight, which is the average mass of an element. He further grouped them into rows (known as periods) and columns (known as groups) based upon their chemical and physical properties.
Mendeleev's original table is remarkably similar to the modern periodic table of elements, despite the fact that he had no idea what atoms were made of or how they behaved. Mendeleev's table understandably did not include many elements that had not yet been discovered in 1869.
Based upon gaps in his original table, though, Mendeleev successfully predicted that several new elements would be discovered. He even predicted what some of their properties would be! That's fairly impressive for a scientist in 1869.
Our modern periodic table of elements organizes elements according to their atomic number, which is the number of protons in each atom of the element. Increasing atomic number generally coincides with increasing atomic mass, which explains why Mendeleev's original table resembles our modern periodic table.
The periodic table lists each element's symbol, atomic number, and atomic weight. As Mendeleev originally conceived, it also groups elements into columns/groups of elements that behave similarly. For example, all of the group 1 elements are alkali metals and all of the group 18 elements are inert gases (also called noble gases).
Is the periodic table complete today? Not necessarily! The current total of elements sits at 118, and that number includes four new elements that were confirmed and added to the periodic table in recent years, completing the seventh row/period of the table.
Are there elements out there that exist beyond the current 118? Possibly! Any new elements would be superheavy elements created in a laboratory by scientists. As new elements continue to be created by scientists, the periodic table will continue to expand.