On December 30, 2015, the International Union of Pure and Applied Chemistry (IUPAC) ratified the discovery of four new chemical elements. The four elements occupy positions 113, 115, 117, and 118 on the periodic table and fill up the seventh row. The four elements have temporary names of ununtrium (113), ununpentium (115), ununseptium (117), and ununoctium (118).
The four elements have been known to scientists for years. For example, element 113 was first announced in 2004. However, IUPAC carefully checks these discoveries and subsequent confirmations before announcing that a new element can be added to the periodic table. In ratifying the discovery, IUPAC has asked the discoverers of the elements (a Japanese team for element 113 and U.S.-Russian collaborations for the other three) to propose names and chemical symbols.
These elements do not exist in nature on Earth and are created through collisions between nuclei of other elements in particle accelerators. Shortly after their creation, they decay into atoms of other elements. The longest-lived of these four, element 113, has an isotope with a half-life of 20 seconds.
Source: http://www.britannica.com/story/four-new-elements-confirmed
