If Rip Van Winkle had slept for 40 years instead of 20 and if he had begun his prolonged snooze in early 1964, he would have been utterly surprised to learn that scientists had synthesized many new elements.
In 1961, Albert Ghiorso and his team in Berkeley, California synthesized the last element in the actinide series. Actinium is the element which has the atomic number 89. The actinide series contains the 14 elements that follow actinium. Their atomic numbers range from 90 to 103. Elements beyond atomic number 103 are called transactinides.
In 1964, Flerov and his coworkers at the Joint Institute for Nuclear Research in the Russian town of Dubna claimed to have synthesized the first transactinide element. They called it kurchatovium in honor of a leading Russian nuclear scientist.
To synthesize elements with an atomic number greater than 100, it is necessary to shoot the nuclei of a light element at a target made of a heavier element. The Dubna team had aimed neon nuclei at a plutonium target. Ghiorso and his Berkeley team could not reproduce the Dubna results, but they synthesized element 104 in a different way. In 1969, they shot carbon nuclei at a target made of atoms of the element californium. Questioning the Russian results, they claimed discovery and called the element rutherfordium in honor of Ernest Rutherford, a New Zealand physicist who discovered that the positive charge of an atom is concentrated in a small central region called the nucleus. Rutherfordium eventually became the element’s official name.
In 1967, the Dubna team announced the synthesis of an element with an atomic number of 105. They again used a neon nucleus as a bullet, but this time they used americium atoms as a target.
In 1970, the Berkeley group produced element 105 in a different way. They used a target made of californium once more, but this time they used nitrogen nuclei as bullets. Their name for the element was hahnium after the German scientist Otto Hahn, who was instrumental in the development of the science of nuclear chemistry.
In the end, neither name became official. The element was called dubnium in honor of the town in which the Russian team had synthesized the element.
The Dubna team synthesized element 106 in June, 1974. They bombarded a lead target with a chromium bullet.
Three months later, the Berkeley team synthesized the same element. They again used a californium target, but oxygen served as the bullet. They proposed the name seaborgium in honor of Glenn Seaborg, who was involved in the discovery of plutonium and other transuranian elements. Because of this, Seaborg received the Nobel Prize for Chemistry in 1951, together with Edwin McMillan, who shares in the credit for the discovery of plutonium.
The name seaborgium was not immediately accepted. The International Union of Pure and Applied Chemistry (IUPAC) makes the final decision on the names of newly discovered elements. In 1994, IUPAC rejected the name seaborgium and adopted a rule that no new element could be named after a living person. However, in 1997, the official climate changed, and seaborgium became the official name of element 106. At the same time, other elements received their final official names, including rutherfordium and dubnium.
Wikipedia: Element Naming Controversy
Jefferson Lab: The Element Rutherfordium
Environmental Chemistry: Element Dubnium – Db
The Periodic Table: The Element Seaborgium