Distribution of Elements on Earth

Heavier elements (Z = 40 or higher) may also have radioactive isotopes with longer half-lives. As a result, some of these radioactive isotopes have not had time to decay completely, and the natural substances are radioactive. Further discussion of isotopic abundances and radioactivity can be found in larger or more specialized sources.  

As atomic mass increases, the ratio of neutrons to protons in stable isotopes gradually increases from 1 1 to 1.6 1 for 92U. There is also a set of nuclear energy levels similar to the electron energy levels described in Chapter 2 that result in stable nuclei with 2, 8, 20, 28, 50, 82, and 126 protons or neutrons. In nature, the most stable nuclei are those with the numbers of both protons and neutrons matching one of these numbers 2He, gO, 2oCa, and gi Pb are examples. 

Theories that attempt to explain the formation of the specific structures of the Earth are at least as numerous as those for the formation of the universe. Although the details of these theories differ, there is general agreement that the Earth was much hotter during its early life, and that the materials fractionated into gaseous, liquid, and solid states at that time. As the surface of the Earth cooled, the lighter materials in the crust solidified and still float on a molten inner layer, according to the plate tectonics 

As an example of the action of water, we can explain the formation of bauxite (hydrated AI2O3) deposits by the leaching away of the more soluble salts from aluminosilicate deposits. The silicate portion is soluble enough in water that it can be leached away, leaving a higher concentration of aluminum. This is shown in the reaction 

FIGURE 1-9 Geochemical Classification of the Elements. (Adapted with permission from P. A. Cox, The Elements, Their Origin, Abundance, and Distribution, Oxford University Press, Oxford, 1990, p. 13.) 

---

Fahrenheit Temperature Scale 11 Distribution of Elements on Earth 47... 

Bence, A.E. (1983) Volcanogenic massive sulfides rtx k/water interactions in ba.saltic systems and their effects on the distribution of the rare earth elements and selected first. series transition elements (abst.). 4th International Symposium on Water-Rock interaction, Mi.sasa, Japan, 48. 

Cobalt is the 32nd most abundant element on Earth even though it makes up only 0.003% of the Earth s crust. It is not found in the free metallic state, despite being widely distributed in igneous rocks as minerals. Its two most common mineral ores are cobaltite (CoAsS) and erythrite [Co lAsO l ]. These ores are placed in blast furnaces to produce cobalt arsenide (COjAs), which is then treated with sulfuric acid to remove the arsenic. Finally, the product cobalt tetraoxide (Co O ) is reduced by heat with carbon (Co O + C — 3Co + 2COf resulting in cobalt metal. 

Phosphorus is one of the most widely distributed elements on earth. It is found as phosphate salts in nearly all igneous rocks and in sedimentary deposits and sea beds. Phosphorus occurs in more than three hundred minerals, usually associated with Ca, Mg, Fe, Sr, Al, Na, and several other metals, and with anions such as silicates, sulfates, oxides, hydroxides, and hahdes. 

Potassium is distributed widely in nature. The metal is too reactive to occur in native elemental form. It is the seventh most abundant element on earth, constituting 2.40% by weight of the earth s crust. It is abundantly present in sea water. Oceans contain 0.07% (wt to volume) potassium chloride. 

Strontium isotopes, though not fractionated easily in nature, are a valuable tool for genetic investigations on rocks and minerals beside their application for dating by the Rb/Sr method. The distribution of elements in the different parts of the earth s crust and mantle depends on their crystal chemistry. Thus,... 

It is now accepted that physical and chemical factors were exclusively responsible for the distribution of elements 4.5 billion years ago when the Earth was formed. Recent evidence suggests that life originated on Earth over 3.5-3.8 billion years ago. Since that time, biological processes have become increasingly important in redistribution of chemical elements and their compounds. 

Phosphorus is one of the most important elements on Earth. It participates in or controls many of the biogeochemical processes occurring in the biosphere. To understand the interaction between P and other biogeochemical processes and elemental distributions, it is necessary to understand the distribution of P on the Earth s surface and the processes that control its distribution. The strategy of this chapter, therefore, is to (1) discuss the chemical forms in which P is present in the environment ... 

The spectral analysis of radiations from the sun and stars, plus other evidence, has revealed a distribution of elements in the universe far different from that on earth. 

The Chemistry in Action essay on p. 62 describes the distribution of the elements on Earth and in the human body. 

Phosphorus (P) is one of the most widely distributed elements on Earth. It s found as phosphate in almost all igneous and sedimentcuy rocks. It s also an essential element for life and provides energy when adenosine triphosphate (ATP) is converted to adenosine diphosphate (ADP) within the cells of your body. It can be found in bones, in DNA, and nucleic acids. Today, it can be found frequently in soda drinks in the form of phosphoric acid. On its own, however, phosphorous is a hazardous material, cmd prolonged exposure can lead to severe burns and illness. 

Vernadsky was also a pioneer in another domain, bio-geochemistry, the science that studies the distribution of elements among plants and animals. This new science inspired A. I. Oparin, who became a leading expert in this field pubhshing his book The Origin of Life on Earth in 1936. 

---