the isotopic composition of all elements
31Mass (mass spectrometry) — This article is about different concepts of mass used in mass spectrometry. For other uses, see mass. The mass recorded by a mass spectrometer can refer to different physical quantities depending on the characteristics of the instrument and the… …
32Iron — Fe redirects here. For other uses, see Fe (disambiguation). This article is about the chemical element. For other uses, see Iron (disambiguation). manganese …
33Nickel — This article is about the chemical element. For other uses, see Nickel (disambiguation). cobalt ← nickel → copper ↑ Ni ↓ Pd …
34Evolutionary history of plants — Plants have evolved through increasing levels of complexity, from the earliest algal mats, through bryophytes, lycopods, ferns and gymnosperms to the complex angiosperms of today. While the simple plants continue to thrive, especially in the… …
35Law of definite proportions — In chemistry, the law of definite proportions, sometimes called Proust s Law, states that a chemical compound always contains exactly the same proportion of elements by mass. An equivalent statement is the law of constant composition, which… …
36Isotopes of calcium — Calcium (Ca) has four stable isotopes (40Ca and 42Ca through 44Ca), plus two more isotopes (46Ca and 48Ca) that have such long half lives that for all practical purposes they can be considered stable. It also has a cosmogenic isotope, radioactive …
37Isotopes of lead — Lead (Pb) has four stable isotopes 204Pb, 206Pb, 207Pb, 208Pb and one common radiogenic isotope 202Pb with a half life of 53,000 years. The standard atomic mass is 207.2(1) u. It is the heaviest discovered element to have a stable isotope. (The… …
38Natural nuclear fission reactor — Geological situation in Gabon leading to natural nuclear fission reactors 1. Nuclear reactor zones 2. Sandstone 3. Uranium ore layer 4. Granite A natural nuclear fission reactor is a uranium deposit where analysis of isotope ratios has shown that …
39Isotopes of thorium — Although thorium (Th) has multiple isotopes, none of these isotopes are stable; however, one isotope is relatively stable (232Th). As such, thorium is considered to be mononuclidic. It has a characteristic terrestrial isotopic composition and… …
40Isotopes of zirconium — Naturally occurring zirconium (Zr) is composed of four stable isotopes, and one extremely long lived radioisotope (96Zr), which decays via double beta decay with the observed half life of 2.0×1019 years [http://www.nndc.bnl.gov/bbdecay/list.html] …
