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Scandium is only the 50th most common element on Earth (35th most abundant element in the crust), but it is the 23rd most common element in the Sun [17] and the 26th most abundant element in the stars. [18] However, scandium is distributed sparsely and occurs in trace amounts in many minerals. [19]
However there are numerous exceptions; for example the lightest exception is chromium, which would be predicted to have the configuration 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4 4s 2, written as [Ar] 3d 4 4s 2, but whose actual configuration given in the table below is [Ar] 3d 5 4s 1.
Atomic number (Z): 21: Group: group 3: Period: period 4: Block d-block Electron configuration [] 3d 1 4sElectrons per shell: 2, 8, 9, 2: Physical properties; Phase at ...
In chemistry and atomic physics, an electron shell may be thought of as an orbit that electrons follow around an atom's nucleus.The closest shell to the nucleus is called the "1 shell" (also called the "K shell"), followed by the "2 shell" (or "L shell"), then the "3 shell" (or "M shell"), and so on further and further from the nucleus.
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.
Gadolinium isotopes have four metastable isomers, with the most stable being 143m Gd (t 1/2 = 110 seconds), 145m Gd (t 1/2 = 85 seconds) and 141m Gd (t 1/2 = 24.5 seconds). The isotopes with atomic masses lower than the most abundant stable isotope, 158 Gd, primarily decay by electron capture to isotopes of europium .
Scandium concentrates in the liver and is a threat to it; some of its compounds are possibly carcinogenic, even though in general scandium is not toxic. [80] Scandium is known to have reached the food chain, but in trace amounts only; a typical human takes in less than 0.1 micrograms per day. [80]
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 ...