The periodic table is considered by many to be the single most important chemistry reference available to scientists and researchers. It provides keys to understanding the building blocks our world is made of and has a seemingly unlimited amount of knowledge hidden in its columns, rows, letters and numbers. The periodic table is a serious and complicated scientific tool, but it's also home to some interesting and fun facts for the whole family.
The periodic table was created in 1869 by the Russian scientist Dmitri Mendeleev. Although at that time not all of the world's elements had been discovered, Mendeleev's system for categorising and arranging the elements by characteristics and atomic number is still in use today.
Elements are added to the periodic table as they are discovered. The table originally started with 65 elements but now includes a total of 110 known elements and 18 periods. The periodic table was last reviewed and accepted by the Union of Pure Applied Chemistry (IUPAC) in 1985.
Making up about 90 per cent of the world by weight, the most abundant element in the universe is hydrogen. It is also the lightest of all the elements and, being found in all organic compounds, is essential to all forms of life.
Carbon has almost 10 million known compounds, which is many times more than any other element. Some of the most common carbon compounds are carbon dioxide, carbon monoxide, chloroform, methane and acetic acid. There are so many carbon compounds that an entire branch of science has been dedicated to their study called organic chemistry.
Francium is one of the rarest elements in the world and results from the breakdown and decay of actinium. It has an extremely short half-life (a matter of minutes), and scientists estimate that there is no more than a few ounces of Francium in existence on the Earth at any given time.
Oxygen is the third most abundant element in the universe and is highly reactive, meaning it likes to pair and form compounds with most other elements. In its pure liquid or solid state, oxygen is a pale shade of blue. Although oxygen is best known for being part of our atmosphere and is 21 per cent of the air we breathe, it is actually even more common in the Earth's crust--making up almost half of it. It also makes up about 66 per cent of the human body and 90 per cent of water, as well as makes up the Earth's protective shield, the ozone layer.
The only letter that does not appear anywhere on the periodic table is the letter J.