Scientists are in their element as they celebrate the 150thanniversary of the periodic table.
The table has tortured physics and chemistry students trying to learn the order of the elements – but is also a triumph of logic.
The periodic table of chemical elements, to give the full name, was arranged by Russian scientist Dmitri Mendeleev – in 1869.
The table is so important that the United Nations designated 2019 the International Year of the Periodic Table to highlight how chemistry can offer solutions to global issues such as growing food, health care and producing energy.
Mendeleev was by no means the first scientist to try to impose some order on the then chaotic table.
How the periodic table works
He decided to group the elements according to properties by listing them above each other. He also left gaps for new additions.
But Mendeleev came before other scientists who discovered the sub-atomic structure of the atom and relied on the atomic weight of an element to decide the order of his table.
Later, scientists realised the atomic number of an element was the same as the number of protons in the nucleus. That led the modern table order to rely on atomic numbers rather than atomic weight.
The table currently consists of 118 elements and is ‘periodic’ according to the energy level of the electrons in each element. The periods are the rows of the table and the electron energy level is higher towards the end of the last row.
The last additions were in December 2015, when four elements joined the list.
Quirky facts about the periodic table
Some other quirky facts about the table of elements include:
- No elements have the letters J or Q in their symbols
- Element names can only refer to:
- a mythological concept or character (including an astronomical object)
- a mineral or similar substance
- a place, or geographical region
- a property of the element
- a scientist
- Only two elements are named after women – Curium after Marie Curie and Meitnerium after Lise Meitner
- Four elements are named after Ytterby, a small village near Stockholm, Sweden. The elements yttrium, terbium, erbium and ytterbium were all discovered in mineral samples from a mine near the village.