Four new chemical elements have been officially added to the periodic table.The International Union of Pure and Applied Chemistryannounced names of the new elements earlier this week.They are Nihonium (Nh), Moscovium (Mc), Tennessine (Ts), and Oganesson (Og).The names were chosen by the scientists who discovered them.All of the elements are man-made, created in labs by nuclear researchers.Those researchers are from Japan, Russia and the United States.Moscovium is named after Moscow, the Russian capital.Oganesson is named in honor of the 83-year-old Russian researcher Yuri Oganessian.Oganesson is only the second element to be named after a living scientist.Tennessine is named after the American state of Tennessee.American researchers named the new element.They work for Oak Ridge National Laboratory and Vanderbilt University,both of which are based in the state.A group of Japanese researchers came up with the name for the fourth new element, Nihonium.The word "Nihon" means Japan in Japanese.Elements can be named for an idea or character in mythology,a mineral, a place, a scientist or a property of the element.The chemistry union usually likes namesthat are easy to translate across major languages.The names must have endings like "-ium," "-ine" or "-on,"depending on the grouping of elements they belong to.The four new names will now be under consideration for five monthsto give time for any possible objections.