- Element 101 : mendelevium; unchanged.
- Thus under optimum conditions, the preparation of only one atom of element 101 per experiment could be expected.
- In 1955, element 101 was discovered and named mendelevium in honor of D . I . Mendeleev, the first to arrange the elements in a periodic manner.
- All of the elements up to einsteinium, element 99, have been checked except for astatine and francium, and fluorine is also known to form compounds with mendelevium, element 101, rutherfordium, element 104, and seaborgium, element 106.
- The target material, einsteinium-253, could be produced readily from irradiating plutonium : one year of irradiation would give a billion atoms, and its three-week half-life meant that the element 101 experiments could be conducted in one week after the produced einsteinium was separated and purified to make the target.
- The Dubna team are therefore officially recognised as the discoverers of nobelium although it is possible that it was detected at Berkeley in 1959 . This decision was criticized by Berkeley the following year, calling the reopening of the cases of elements 101 to 103 a " futile waste of time ", while Dubna agreed with the IUPAC's decision.
- In a decision announced Monday in Chemical and Engineering News, a committee of the International Union of Pure and Applied Chemistry, or IUPAC, recommended changes in the provisional names assigned to Elements 101 through 109 . The changes, which must be ratified next August by the full council of the British-based organization, drew angry responses from several leading American chemists and nuclear physicists.