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A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Of the 94 natural elements, eighty have a stable isotope and one more has an almost-stable isotope (with a half-life of 2.01×10 19 years, over a billion times the age of the universe). [15] [b] Two more, thorium and uranium, have isotopes undergoing radioactive decay with a half-life comparable to the age of the Earth.
No elements heavier than boron were produced in the Big Bang. As a result, the primordial abundance of atoms (or ions) consisted of ~75% 1 H, 25% 4 He, and 0.01% deuterium, with only tiny traces of lithium, beryllium, and perhaps boron. [23] Subsequent enrichment of galactic halos occurred due to stellar nucleosynthesis and supernova ...
Chemical elements that are not synthesised; Classical element, the concept in ancient Greece of earth, water, air or fire; Natural abundance, the relative amounts of isotopes of a chemical element; Abundance of the chemical elements, the relative occurrence of chemical elements
Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry.
This is an accepted version of this page This is the latest accepted revision, reviewed on 22 January 2025. Periodic table of the elements with eight or more periods Extended periodic table Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium ...
Lavoisier writes the first modern list of chemical elements – containing 33 elements including light and heat but omitting Na, K (he was unsure of whether soda and potash without carbonic acid, i.e. Na 2 O and K 2 O, are simple substances or compounds like NH 3), [91] Sr, Te; some elements were listed in the table as unextracted "radicals ...
This is a list of chemical elements and their atomic properties, ordered by atomic number (Z).. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.