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Chemical element with atomic number 12 (Mg) Magnesium, 12 Mg Magnesium Pronunciation / m æ ɡ ˈ n iː z i ə m / (mag- NEE -zee-əm) Appearance shiny grey solid Standard atomic weight A r °(Mg) [24.304, 24.307] 24.305 ± 0.002 (abridged) Magnesium in the periodic table Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus ...
Like the periodic table, the list below organizes the elements by the number of protons in their atoms; it can also be organized by other properties, such as atomic weight, density, and electronegativity. For more detailed information about the origins of element names, see List of chemical element name etymologies.
This is a list of chemical elements and their atomic properties, ... Name Symbol Average atomic mass Electronegativity ... 12.0107(8) 2.55: 11.2603: 70: 170: 77: 4 7:
Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol; those for hydrogen, helium, and lithium are respectively H, He, and Li. [6] Neutrons do not affect the atom's chemical identity, but do affect its weight.
IUPAC publishes one formal value for each stable chemical element, called the standard atomic weight. [17] [1]: Table 1 Any updates are published biannually (in uneven years). In 2015, the atomic weight of ytterbium was updated. [17] Per 2017, 14 atomic weights were changed, including argon changing from single number to interval value. [18] [19]
For example, the relative isotopic mass of a carbon-12 atom is exactly 12. For comparison, the atomic mass of a carbon-12 atom is exactly 12 daltons. Alternately, the atomic mass of a carbon-12 atom may be expressed in any other mass units: for example, the atomic mass of a carbon-12 atom is 1.992 646 882 70 (62) × 10 −26 kg.
The standard atomic weight (commonly called "atomic weight") of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance, relative to the atomic mass unit. This number may be a fraction that is not close to a whole number. For example, the relative ...
Copernicium is a synthetic chemical element; it has symbol Cn and atomic number 112. Its known isotopes are extremely radioactive , and have only been created in a laboratory. The most stable known isotope , copernicium-285, has a half-life of approximately 30 seconds.