You think to prometium and technetium; but today these chemical elements are considered as being natural.
All the elements after Uranium(atomic no. 92) have been artificially produced.
"Binding energy." Absorption of neutrons by heavy elements, and fission of those heavy elements into lighter "fragments". The "lighter fragements" have a greater net binding energy than the heavier elements did.
Up to uranium elements are made by stellar nuclear synthesis; after uranium elements are man made.
Uranium can form chemical compounds with the majority of other elements.
Uranium form chemical compounds with the majority of the other elements.
Splitted uranium is not uranium, but other two lighter elements.
Uranium is not lighter but heavier than many of the other elements; the density of uranium is 19,05 g/cm3 and the atomic weight is 238,02891.
The elements formed in particle accelerators are usually called Synthetic Elements or Artifically Produced Elements. They are all Transuranium Elements (higher on the periodic table than Uranium), and twenty have been produced so far. Most of them disintegrate within a fraction of a second, some of them in such a short time that it is difficult to verify whether an element has been created or not.
Uranium and radium, and a number of others, are natural elements found in the ground, and they are radioactive.
Today all elements from hydrogen to californium are considered as natural; lighter elements than uranium as francium, promethium and technetium are now impossible to be detected only by chemical methods.
All the elements after Uranium(atomic no. 92) have been artificially produced.
All elements lighter than Uranium (atomic number: 92) occur naturally except for technetium (43).
"Binding energy." Absorption of neutrons by heavy elements, and fission of those heavy elements into lighter "fragments". The "lighter fragements" have a greater net binding energy than the heavier elements did.
In the past promethium and technetium were considered as artificial elements; now extreme traces of these elements were discovered in the nature.
Boron is lighter than carbon and uranium.
All of it will eventually break up into lighter elements.All of it will eventually break up into lighter elements.All of it will eventually break up into lighter elements.All of it will eventually break up into lighter elements.
Now all the elements lighter than uranium are discovered in the nature, even if in extremely small quatities. In the past promethium, technetium, etc. were considered only as artificial elements.