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.
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.
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.
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.
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"
All elements having atomic no. greater than 92 (Excluding 61) are not naturally occurring.
http://education.jlab.org/itselemental/tableofelements5dc.pdf
Because it is intended to represent all known elements, not only those which exist in nature.
well buddy there are only 92 elements in the periodic table occurring naturally on earth.. the rest are all man made...
Yes!
Not all the elements occur naturally; some elements are man-made.
There are 92 elements found naturally in the universe.
There are 90 elements that exist naturally.
These elements exist also naturally - in infinitesimal amounts - in the Earth crust.But practically are artificial elements.
Native elements.
Because it is intended to represent all known elements, not only those which exist in nature.
Most of the naturally occurring elements are transition metals.
No - not naturally, it usually exist with other elements. To achieve a pure form, MnO2 needs to be heated with carbon to remove the oxygen.
All are radioactive, artificial elements (but note that Np and Pu can exist also naturally in extremely low concentrations).
Many elements exist naturally in more than one isotopic form, each of which has a different atomic mass number. However, all of these isotopes have almost identical chemical properties, and it is therefore more useful to chemists to list elements in the table, along with the average atomic mass resulting from any mixture of isotopes that naturally occurs.
well buddy there are only 92 elements in the periodic table occurring naturally on earth.. the rest are all man made...
There are 90 naturally occurring elements. The other 28 are synthetic. Refer to the related link for a printable colored periodic table that identifies the artificially prepared elements.
Yes!
Simply because they exist in their natural state. Most elements are naturally found in compounds (ores, minerals) and must be processed to access the actual elements.