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List of chemical elements. 118 chemical elements have been identified and named officially by IUPAC. 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]
Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium ...
A chemical element is a chemical substance that cannot be broken down into other substances by chemical reactions. The basic particle that constitutes a chemical element is the atom. Elements are identified by the number of protons in their nucleus, [ 1] known as the element's atomic number. [ 2] For example, oxygen has an atomic number of 8 ...
Prima facie. Prima facie ( / ˌpraɪmə ˈfeɪʃi, - ʃə, - ʃiiː /; from Latin prīmā faciē) is a Latin expression meaning "at first sight", [ 1] or "based on first impression". [ 2] The literal translation would be "at first face" or "at first appearance", from the feminine forms of primus ("first") and facies ("face"), both in the ...
Base rate fallacy – making a probability judgment based on conditional probabilities, without taking into account the effect of prior probabilities. [6] Conjunction fallacy – the assumption that an outcome simultaneously satisfying multiple conditions is more probable than an outcome satisfying a single one of them.
The primitive and cubic close-packed (also known as face-centered cubic) unit cells. In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals . There are three main varieties of these crystals:
Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactive chemical elements, being the second-lowest in the reactivity series. It is solid under standard conditions. Gold often occurs in free elemental (native state), as nuggets or grains, in rocks, veins, and alluvial deposits.
Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Precious metals, particularly the noble metals, are more corrosion resistant and less chemically reactive than most elements. They are usually ductile and have a high lustre. Historically, precious metals were important as currency but are now ...