There are 118 elements on the periodic table. Atoms of each element contain different numbers of protons (atomic number), as well as a unique name and element symbol. The first element, with atomic number 1, is hydrogen (H). The last element is oganesson (Og), with atomic number 118. The periodic table lists the chemical elements in order of increasing atomic number, but also organizes them according to common properties and trends. So, the elements in a group or column share similar valence electron behavior, while the elements in a period or row share the same outer electron shell.
There Weren’t Always 118 Elements
Older periodic tables list fewer than 118 elements. For example, a periodic table from the 1960s only had around 100 elements. By 1900, there were 82 known elements. In the year 1800, there were only 30 elements. Mendeleev’s first periodic table only included 28 elements!
Recently Discovered Elements
Ancient people knew about 10 elements: carbon, copper, gold, iron, lead, mercury, silver, sulfur, tin, and zinc. Arsenic, antimony, and bismuth were discovered prior to 1500 AD, while phosphorus, cobalt, and platinum were discovered by 1750.
Most of the other natural elements were identified by 1900. Technetium became the first synthetic element in 1937. The first transuranium element to be discovered (neptunium) was found in 1940.
The last four elements to be discovered were officially recognized by the IUPAC in January, 2016. Their names and symbols became official on November 28, 2016. These four elements are nihonium (Nh), moscovium (Mc), tennessine (Ts), and oganesson (Og), with atomic numbers 113, 115, 117, and 118, respectively.
Are All of the Elements Discovered?
While it’s unlikely we’ll find any additional natural elements, scientists will make new synthetic elements eventually. So, it’s less a matter of discovery and more about element synthesis. Good candidates for the next element include 119 (ununennium) and 120 (unbinilium), but there may be elements with higher atomic numbers that are more stable and easier to make.
How Many Elements Occur Naturally?
Of the 118 elements, 98 have been found in nature. Of the 98 naturally-occurring elements, 88 occur in appreciable amounts. 10 elements only exist in trace quantities, usually because they decay into another element almost as soon as they form.
References
- Ball, P. (2004). The Elements: A Very Short Introduction. Oxford University Press. ISBN 978-0-19-284099-8.
- Chapman, Kit (2019) “The first synthetic element”. Nature. 565: 570-571. doi:10.1038/d41586-019-00236-4
- Emsley, J. (2003). Nature’s Building Blocks: An A–Z Guide to the Elements. Oxford University Press. ISBN 978-0-19-850340-8.
- IUPAC (1997). “Chemical Element”. Compendium of Chemical Terminology (2nd ed.). (the “Gold Book”). doi:10.1351/goldbook.C01022
- Sanderson, K. (2006). “Heaviest element made – again”. Nature. doi:10.1038/news061016-4