It's Elementary: The Periodic Table Quiz

In 1869, Russian scientist Dmitri Ivanovich Mendeleev published the first (truly famous) periodic table of elements. His genius was that he organized elements in the table in a logical manner a century and a half before people really understood much about the composition of matter.

Mendeleev left blank spaces for new elements that would be discovered soon, and he was right — scandium, germanium and gallium were all identified a few years later, making the scientist wildly famous. (The vodka story is a myth, by the way.)

In 1869, science had yet to define even half of the current number of elements. There were just 63 elements on Mendeleev’s first table.

As of 2019, 118 elements are on the periodic table. The first 98 occur naturally; the others have been created by researchers in nuclear reactors or in laboratory settings.

The horizontal rows are called periods while the vertical columns are called groups.

Fluorine is not part of this group of noble gases (also known as "inert gases.") Fluorine actually is in the second column from the right, the halogen family.

Each element has a number, called the atomic number, which is the number of protons in the nucleus of each element's atom. So, cobalt has an atomic number of 27, which means it has 27 protons.

Technetium does occur naturally in Earth’s crust, but only a few thousand tons are present at any given time. The vast majority of this element is artificially produced by humans as a result of nuclear reactor waste.

Hydrogen's atomic number is 1, which means it has 1 proton. It's the lightest element on the table.

Of the 98 naturally occurring elements on Earth, astatine is the rarest, appearing only as other elements decay. It’s so radioactive that it tends to vaporize itself, a primary reason that no scientist has ever snagged a totally pure sample of this element.