Patterns of abundance
Information on the abundance of elements comes into existence from various sources. Various elements are obtained by the minerals in the Earth's crust. So the availability of elements relies on the crustal abundance that can be estimated through analyzing representative samples of minerals. The abundances of elements change extremely, from common ones like oxygen and silicon (correspondingly 46% and 27% by mass) down to ones such as Os, Ir and Xe (one part in 1010 or less). The most common elements are listed in Table 1.
The crust is thin and rests on the Earth's mantle that consecutively surrounds the metallic core. Like these inner regions are not straight accessible, information on their composition arrives from less direct sources, that is including meteorites, that fall from space, and that is are derived from one or more planets which broke up in the early on stages of formation of the
Table 1. The most abundant elements in the crust, the whole Earth and the Solar System (mass fraction, with elements listed in order of decreasing abundance within each range)
Solar System. Estimates of the complete abundance of elements in the whole Earth depict some variations from the crust. Iron is the main element in the core and has a identical abundance to oxygen in the Earth like a whole. The Solar System is conquered in mass through the Sun. Estimates of elemental composition could be obtained from the spectrum of sunlight, that depicts atomic absorption lines. By far the most abundant elements Hydrogen and helium, followed at a level of less than 1% through oxygen and carbon. This pattern of abundances is general of the Universe as a whole, that is dominated through H and He in an atomic ratio of approximately 10:1, all other elements jointly making up only 1%.
Two very dissimilar factors are significant in determining the abundance patterns displayed in Table 1. The entire abundance in the Universe and in the Solar System relies on how elements were made through nuclear reactions. The very dissimilar distribution in the Earth and its constituent parts is a consequence of subsequent chemical separation of elements through the formation of the planets.