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Silicon (14 Si) has 25 known isotopes, with mass numbers ranging from 22 to 46. 28 Si (the most abundant isotope, at 92.23%), 29 Si (4.67%), and 30 Si (3.1%) are stable. The longest-lived radioisotope is 32 Si, which is produced by cosmic ray spallation of argon.
Isotopic variations in groundwater and riverine transports contribute to variations in oceanic 30 Si values. Currently, there are substantial differences in the isotopic values of deep water in the world's ocean basins. Between the Atlantic and Pacific oceans, there is a deep water 30 Si gradient of greater than 0.3 parts per thousand.
Relative atomic mass (Atomic weight) was originally defined relative to that of the lightest element, hydrogen, which was taken as 1.00, and in the 1820s, Prout's hypothesis stated that atomic masses of all elements would prove to be exact multiples of that of hydrogen. Berzelius, however, soon proved that this was not even approximately true ...
The calculation is exemplified for silicon, whose relative atomic mass is especially important in metrology. Silicon exists in nature as a mixture of three isotopes: 28 Si, 29 Si and 30 Si. The atomic masses of these nuclides are known to a precision of one part in 14 billion for 28 Si and about one
The calculation is exemplified for silicon, whose relative atomic mass is especially important in metrology. Silicon exists in nature as a mixture of three isotopes: 28 Si, 29 Si and 30 Si. The atomic masses of these nuclides are known to a precision of one part in 14 billion for 28 Si and about one
6.674 30 (15) × 10 −11 m 3 ⋅ ... atomic mass constant: ... each uncertainty as stated reflects our lack of knowledge of the corresponding value as expressed in ...
This is because the mass–energy is a convex function of atomic number, ... 29 Si 30 P 31 S 32 Cl 33 Ar 34 K 35 Ca V 24; 16 21 B 22 C 23 N 24 O 25 F 26 Ne 27 Na 28 ...
The mass number should also not be confused with the standard atomic weight (also called atomic weight) of an element, which is the ratio of the average atomic mass of the different isotopes of that element (weighted by abundance) to the atomic mass constant. [9] The atomic weight is a mass ratio, while the mass number is a counted number (and ...