Atomic Mass Of Calcium
In 1959, a letter in the Bulletin of the Atomic Scientists was the start of a successful campaign to stop the Atomic Energy Commission dumping radioactive waste in the sea 19 kilometres from Boston. In 1962, Linus Pauling won the Nobel Peace Prize for his work to stop the atmospheric testing of nuclear weapons, and the 'Ban the Bomb' movement. This is a list of chemical elements, sorted by atomic mass (or most stable isotope) and color coded according to type of element.Each element's atomic number, name, element symbol, and group and period numbers on the periodic table are given. The number in parenthesis gives the uncertainty in the 'concise notation' dis given in parenthesis next to the least significant digits to which it. Atomic weight, ratio of the average mass of a chemical element’s atoms to some standard. Since 1961 the standard unit of atomic mass has been one-twelfth the mass of an atom of the isotope carbon-12. Atomic weight is measured in atomic mass units (amu), also called daltons.
| Isotope | Atomic mass (Da) | Isotopic abundance (amount fraction) |
|---|---|---|
| 40Ca | 39.962 5909(2) | 0.969 41(156) |
| 42Ca | 41.958 618(1) | 0.006 47(23) |
| 43Ca | 42.958 766(2) | 0.001 35(10) |
| 44Ca | 43.955 482(2) | 0.020 86(110) |
| 46Ca | 45.953 69(2) | 0.000 04(3) |
| 48Ca | 47.952 5229(6) | 0.001 87(21) |
Atomic Mass Of Calcium 42
In 1983, the Commission with its liberalized policy on uncertainties,was able to recommend as standard atomic weight Ar(Ca) = 40.078(4) weighted toward the mass-spectrometricmeasurements. Moreover, the stated uncertainty includes all chemical,x-ray, and mass-spectrometric measurements believed to be significant by the Commission, as enumerated inits 1983 report.
There is evidence for minor isotope fractionation of calcium in Nature, causing variability ofAr(Ca) in normal sources that is within the uncertainty of the standard atomic weight. Variations inn(44Ca)/n(40Ca) can be reported as δ44Ca values relative to the calcium carbonate reference materialNIST-SRM 915a. A recent compilation yielded a range of published δ44Ca values in naturalsamples from a low of -2.17 ‰ in a cougar bone with Ar(Ca) = 40.0778 to a high of +2.76 ‰ in egg white with Ar(Ca) = 40.0784.Elemental calcium with as δ44Ca = -6.0 ‰ (Ar(Ca) = 40.0773) also has beenreported. Variations in the isotopic composition of marine calcium have occurred over the last 80 Ma.
In addition, there are many reports of anomalous isotopic composition of some minor samples of Ca, some of which may have arisen from the decay of 40K to 40Ca. The annotation 'g' is therefore maintained for this element. 41Ca is an extinct radioisotope (with a half-life of 0.1 Ma), which can be used to date the early history of the solar system through itsdecay to 41K.
Atomic Weight Of Calcium
© IUPAC 2003
Atomic Mass Of Calcium 40
CIAAW
Atomic Mass Of Calcium Phosphate
Calcium
Ar(Ca) = 40.078(4) since 1983
The name derives from the Latin calx for 'lime' (CaO) or 'limestone' (CaCO3) in which it was found.It was first isolated by British chemist Humphry Davy in 1808 with help from the Swedish chemist JönsJacob Berzelius and the Swedish court physician M. M. af Pontin.
Isotopic reference materials of calcium.