Chemistry · Periodic Classification Of Properties · NEET
'Trans' means beyond. 'Uranium' has atomic number 92. So transuranium elements are all elements with atomic number greater than 92 (Z = 93 and above). They sit after uranium in the periodic table. Examples: neptunium (93), plutonium (94), americium (95), and heavier ones up to the newest lab-made elements.
They are man-made (artificially produced). NCERT says the recently discovered elements are man-made. Almost all transuranium elements do not occur naturally. Scientists make them in labs by hitting heavy atoms with fast-moving particles like neutrons. This is why they are also called synthetic or artificial elements.
Yes, this is a common trap. NCERT notes that neptunium and plutonium are ALSO found in tiny traces in pitchblende (an ore of uranium). So a very small natural amount exists. But the useful quantities we use are all made in the lab. For NEET, remember: transuranium elements are mainly man-made; only trace natural amounts of Np and Pu exist.
NCERT states the Periodic Law revealed analogies among the 94 naturally occurring elements. Elements up to uranium (92) occur naturally, and tiny natural traces of neptunium (93) and plutonium (94) exist in uranium ore. Elements beyond that are all made artificially by scientists.
Glenn T. Seaborg did major work. Starting with the discovery of plutonium in 1940, he and his team found all the transuranium elements from atomic number 94 to 102. This work made scientists move the actinoids below the lanthanoids in the periodic table. Seaborg won the Nobel Prize in Chemistry in 1951, and element 106 is named Seaborgium (Sg) after him.
When a new element is made, IUPAC gives it a temporary (provisional) name built from its atomic number digits using numerical roots: nil = 0, un = 1, bi = 2, tri = 3, quad = 4, pent = 5, hex = 6, sept = 7, oct = 8, enn = 9. For example, element 106 = un-nil-hex + ium = Unnilhexium (later named Seaborgium). This is a very common NEET question.
Most transuranium elements are unstable and radioactive with short half-lives. NCERT calls them 'artificially produced short-lived elements.' They decay quickly into lighter elements, so any that formed long ago on Earth have already broken down. That is why we must keep making them in labs.
Match the IUPAC provisional names with their IUPAC official names. (a) Unnilunium (b) Unniltrium (c) Unnilhexium (d) Unununnium with (i) Mendelevium (ii) Lawrencium (iii) Seaborgium (iv) Darmstadtium. Which one is correct?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Neptunium, atomic number 93. It is the first element that comes after uranium (92), so it is the first transuranium element.
No. Uranium has atomic number 92. Transuranium means beyond uranium, so only elements with atomic number 93 and higher count. Uranium itself is the boundary, not a transuranium element.
Almost all recently discovered man-made elements are transuranium (Z above 92). A few artificial elements like technetium (43) and promethium (61) lie below uranium, but for NEET the man-made group you focus on is the transuranium set.
NEET asks direct facts: how many elements are known, how many occur naturally (94), who discovered them (Seaborg), and especially IUPAC naming of heavy elements using numerical roots. These are easy, high-scoring one-mark ideas if you memorise the roots.
Element 106 is Seaborgium (Sg), named to honour Glenn T. Seaborg, who discovered many transuranium elements and won the 1951 Nobel Prize in Chemistry.
