Atomic number consistent with the modern practice of ordering the elements by proton number, "Z", but that number was not known or suspected at the time. A simple numbering based on periodic table position was never entirely satisfactory, however. Besides the case of iodine and tellurium, later several other pairs of elements (such as argon and potassium, cobalt and nickel) were known to have nearly identical or reversed atomic weights, thus requiring their placement in the periodic table to be determined by their chemical properties. However the gradual identification of more and more chemically similar lanthanide elements, whose atomic number was not
Synthetic element used for many existing synthetic elements, while the name "rutherfordium" (chosen by the American team) was accepted for element 104. Meanwhile, the American team had discovered seaborgium, and the next six elements had been discovered by a German team: bohrium, hassium, meitnerium, darmstadtium, roentgenium, and copernicium. Element 113, nihonium, was discovered by a Japanese team; the last five known elements, flerovium, moscovium, livermorium, tennessine, and oganesson, were discovered by Russian–American collaborations and complete the seventh row of the periodic table. No element with an atomic number greater than 99 has any use outside of scientific research, as they have extremely