What do you call elements that do not exist naturally?

Answer 1

First of all, let's realize what the term "not naturally occurring" means. The natural abundance of 85-Astatium is estimated to be around 10-24 %, which gives the content of this element on Earth around 600g of At in the whole Earth. And keep in mind, that the most stable isotope, At-210, has a half-life of eight hours. So it is reasonable to say that it is not existing naturally. --- The most widely accepted list of artificial elements includes: 43-Technetium, 61-Prometium. The traces of elements 85, 87, 93 and even 94 were found in nature, as these are by-products of the natural decay of uranium or thorium. Generally we say these don't occur naturally, because their content is within the range of 10-10 % to 10-16 %. All elements heavier than plutonium (atomic number 95 and higher) don't exist as Natural Resources of our planet. The elements 84, 86, 88, 89, 91 are sometimes treated as natural or artificial - depends on the criteria used. --- If we take into account the elements which were DISCOVERED in the nuclear research centers and not extracted from the natural minerals, we get: 43, 61, 85, 93 and above.

Answer 2

First of all, let's realize what the term "not naturally occurring" means. The natural abundance of 85-Astatium is estimated to be around 10-24 %, which gives the content of this element on Earth around 600g of At in the whole Earth. And keep in mind, that the most stable isotope, At-210, has a half-life of eight hours. So it is reasonable to say that it is not existing naturally. --- The most widely accepted list of artificial elements includes: 43-Technetium, 61-Prometium. The traces of elements 85, 87, 93 and even 94 were found in nature, as these are by-products of the natural decay of uranium or thorium. Generally we say these don't occur naturally, because their content is within the range of 10-10 % to 10-16 %. All elements heavier than plutonium (atomic number 95 and higher) don't exist as Natural Resources of our planet. The elements 84, 86, 88, 89, 91 are sometimes treated as natural or artificial - depends on the criteria used. --- If we take into account the elements which were DISCOVERED in the nuclear research centers and not extracted from the natural minerals, we get: 43, 61, 85, 93 and above.

Answer 3

Any element with an atomic number of 95 or more does not occur naturally on Earth. In addition, the elements technetium and promethium do not occur often enough, and are included in those that don't occur naturally. See the related link for a list of naturally existing and synthetic elements, and explanations for why this is so.

Answer 4

The elements that are naturally occurring are all the elements with an atomic number of 92 or less. So Uranium is the last and heaviest natural element. But Technetium and Promethium come before Uranium and are synthetic.

Answer 5

89 elements are considered to occur naturally the others are not,the question is how many elements are 'known' up till now?

Most people think it to be about 120.

Naturally occurring elements (89) in alphbetical order:

"actinium", "aluminum", "antimony", "argon", "arsenic", "barium", "beryllium", "bismuth", "boron", "bromine", "cadmium", "calcium", "carbon", "cerium", "cesium", "chlorine", "chromium", "cobalt", "copper", "dysprosium", "erbium", "europium", "fluorine", "francium", "gadolinium", "gallium", "germanium", "gold", "hafnium", "helium", "holmium", "hydrogen", "indium", "iodine", "iridium", "iron", "krypton", "lanthanum", "lead", "lithium", "Lutetium", "Magnesium", "Manganese", "Mercury", "Molybdenum", "Neodymium", "Neon", "Nickel", "Niobium", "Nitrogen", "Osmium", "Oxygen", "Palladium", "Phosphorus", "Platinum", "Polonium", "Potassium", "Praseodymium", "Protactinium", "Radium", "Radon", "Rhenium", "Rhodium", "Rubidium", "Ruthenium", "Samarium", "Scandium", "Selenium", "Silicon", "Silver", "Sodium", "Strontium", "Sulfur", "Tantalum", "Tellurium", "Terbium", "Thallium", "Thorium", "Thulium", "Tin", "Titanium", "Tungsten", "Uranium", "Vanadium", "Xenon", "Ytterbium", "Yttrium", "Zinc", "Zirconium"

Answer 6

All elements having atomic no. greater than 92 (Excluding 61) are not naturally occurring.

http://education.jlab.org/itselemental/tableofelements5dc.pdf