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A calcium atom has twenty electrons, with electron configuration [Ar]4s 2. Like the other elements placed in group 2 of the periodic table, calcium has two valence electrons in the outermost s-orbital, which are very easily lost in chemical reactions to form a dipositive ion with the stable electron configuration of a noble gas, in this case ...
The US Institute of Medicine (IOM) established Recommended Dietary Allowances (RDAs) for calcium in 1997 and updated those values in 2011. [6] See table. The European Food Safety Authority (EFSA) uses the term Population Reference Intake (PRIs) instead of RDAs and sets slightly different numbers: ages 4–10 800 mg, ages 11–17 1150 mg, ages 18–24 1000 mg, and >25 years 950 mg. [10]
Calcium-48 is a scarce isotope of calcium containing 20 protons and 28 neutrons.It makes up 0.187% of natural calcium by mole fraction. [1] Although it is unusually neutron-rich for such a light nucleus, its beta decay is extremely hindered, and so the only radioactive decay pathway that it has been observed to undergo is the extremely rare double beta decay (2β).
Calcium oxalate is insoluble in water, but is soluble in mineral acids. Ca 2+ + (COO) 2 (NH 4) 2 → (COO) 2 Ca + NH 4 + Sr 2+ Strontium ions precipitate with soluble sulfate salts. Sr 2+ + Na 2 SO 4 → SrSO 4 + 2Na + All ions of alkaline earth metals form white precipitate with ammonium carbonate in the presence of ammonium chloride and ammonia.
Calcium-60 is the heaviest known isotope as of 2020. [1] First observed in 2018 at Riken alongside 59 Ca and seven isotopes of other elements, [ 26 ] its existence suggests that there are additional even- N isotopes of calcium up to at least 70 Ca, while 59 Ca is probably the last bound isotope with odd N . [ 27 ]
Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below.
This is the energy per mole necessary to remove electrons from gaseous atoms or atomic ions. The first molar ionization energy applies to the neutral atoms. The second, third, etc., molar ionization energy applies to the further removal of an electron from a singly, doubly, etc., charged ion.
A calcium channel is an ion channel which shows selective permeability to calcium ions. It is sometimes synonymous with voltage-gated calcium channel, [1] which are a type of calcium channel regulated by changes in membrane potential. Some calcium channels are regulated by the binding of a ligand.