Still using an old science textbook? It's time to get a new one then, after four new super-heavy elements were added to the periodic table recently.
The International Union of Pure and Applied Chemistry (IUPAC), the US-based global authority on chemistry, had announced on Dec 30 last year that the table's seventh row was now complete.
Elements 113, 115, 117 and 118 were added to the table - its first update since 2011 - and will be named in the coming months by the scientific teams who discovered them.
They will be known temporarily by their working names of ununtrium (Uut or 113), ununpentium (Uup or 115), ununseptium (Uus or 117), and ununoctium (Uuo or 118).
All four are synthetic and were discovered by slamming light nuclei into each other and tracking the decay of radioactive super-heavy elements (which exist only very briefly before decaying into other elements), reported The Guardian.
IUPAC awarded the discovery of element 113 to a team of scientists from Japan's Riken Institute after they successfully created it three times between 2004 and 2012.
It will be the first element on the table to be named in Asia.
The discovery of the other three elements were claimed by a Russian-American team from the Joint Institute for Nuclear Research in Dubna, the Oak Ridge National Laboratory in Tennessee and the Lawrence Livermore National Laboratory in California.
With the periodic table now looking complete - till its next update, at least - here are some interesting facts about the universal chart used by scientists, teachers and students.
Who came up with the table?
Although several scientists had been known to present their own tables earlier, Russian chemist Dmitri Mendeleev's version - a list arranged in order of the elements' increasing atomic weight - was the first to gain widespread acceptance among the scientific community in 1869.
The modern day version of the table, however, is organised in a grid system and orders the elements by increasing atomic number.
How do you read the table?
There are seven rows, called periods, and 18 columns, called groups, in the table.
Elements in the same group share similar properties. Those in the same period have the same number of atomic orbitals (the wave-like behaviour of either one or a pair of electrons in an atom) - for instance, the first period only has two elements, hydrogen and helium, with only a single orbital.
Most elements on the table are metals divided into six broad categories - alkali metals, alkaline earths, basic metals, transition metals, lanthanides and actinides. They are located on the left, separated from the non-metals on the right by a zig-zag line.
Lanthanides and actinides, often called "inner transition metals", are commonly hived off as a separate section under the main table as including all 30 - including Uranium - would make the table too wide.
The table is a useful tool for people to derive relationships between the different properties of the elements. It can also help predict the properties of new elements that have yet to be discovered or created.
How many elements are there?
Currently, there is only room for 118 elements.
Of the 118, 90 - 1 through 92, with the exception of elements 43 (Technetium, Tc) and 61 (Promethium, Pm) - occur naturally on Earth, although some are extremely rare and can only be found in small quantities.
The rest are synthetic. Technetium was the first element to be made artificially; the silvery grey metal was found in 1936 as part of an experiment conducted in an Italian university.
An eighth period could be added to the table once elements 119 (Ununennium) and 120 (Unbinilium) have been verified. Attempts to synthesise both elements have been unsuccessful thus far.
How are new elements named?
According to the IUPAC, new elements can be named after a mythological concept, a mineral, a place or country, a property or a scientist. After initial acceptance, the element's name and two-letter symbol are put up for public review for five months before the IUPAC Council makes its final decision.
The element Einsteinium (Es), discovered in 1952, was named in honour of renowned scientist Albert Einstein, while Europium (Eu) is named after the continent of Europe after it was isolated in 1901.
Thorium (Th) gained its name from Thor, the Norse God of Thunder, upon its discovery in 1828. It is currently being used as a nuclear fuel due to its radioactivity.
The Riken Institute had earlier said that the name Japonium (in honour of Japan) might be proposed for element 113.
When were new elements last added to the table?
The table's last major revision occurred in June 2011, when elements 114 and 116 were also discovered by a joint Russian-American team from Dubna's Joint Institute for Nuclear Research and California's Lawrence Livermore National Laboratory.
Their names were ratified by the IUPAC nearly a year later on May 30, 2012 - element 114 became known as Flerovium (Fl) and element 116, Livermorium (Lv).
Both are highly radioactive and were the heaviest elements on the table until the recent discovery of elements 115, 117 and 118.
Sources: International Union of Pure and Applied Chemistry website, AFP, BBC, Chemistry.about.com