Elements in earth’s crust

Abundance of elements in earth s crust, see Elements, abundance in earth s crust Acetaldehyde structure, 332 Acetamide, 338 Acetanilide, 344 Acetic acid in biochemistry, 428 structure, 333 Acetone... 

Elemental uranium, crystal structures of, 25 409. See also Uranium (U) Elementary reaction, 21 336 Element/isotope ratios, in fine art examination/conservation, 11 419 Element mapping, in fine art examination/ conservation, 11 406 Element names/symbols, 17 386-387 transfermium, 17 387t Elements, in earth s crust, 26 23 a-Eleostearic acid, physical properties, 5 33t... 

To return to our case study of iron, the equilibrium concentration of Fe(III) is ultimately controlled by its mineral solubility. Since atmospheric dust is a major source of new iron to the ocean, its solubility is a matter of hot debate. If the solubility is low, the particulate iron is likely to settle out of the euphotic zone before it can be assimilated by plankton. Iron is one of the most abundant elements in Earth s crust, so it is not surprising that concentrations in dust are high, ranging from 3 to 5% dry weight. 

Plutonium has a short half-life (24,360 years), so any plutonium initially in Earth s crust has long since decayed. The same is true for any heavier elements with even shorter half-lives from which plutonium might originate. Trace amounts of plutonium can occur naturally in U-238 concentrations, however, as a result of neutron capture, where U-238 becomes U-239 and after beta emission becomes Np-239 and after further beta emission becomes Pu-239. (There are elements in Earth s crust with half-lives even shorter than plutonium s, but these are the products of uranium decay—between uranium and lead in the periodic table of elements.)... 

Elemental iron, the major element in Earth s core, is the fourth most abundant element in Earth s crust (about 5.0% by mass overall, 0.5%-5% in soils, and approximately 2.5 parts per billion in seawater.) In the crust, iron is found mainly as the oxide minerals hematite, Fe203, and magnetite, Fe304. Other common mineral forms are siderite, FeC03, and various forms of FeO(OH). Iron is an essential element in almost all living organisms. In the human body, its concentration ranges between 3 and 380 parts per million (ppm) in bone, 380-450 ppm in blood, and 20-1,400 ppm in tissue. 

Figure 1.2.8. The abundance of elements in Earth s crust. Adapted with permission from Steven I. Dutch, "Periodic Table of Elemental Abundance," Journal of Chemical Education 76 (1999) 356-58.

Lead is thought to be the thirty-sixth most abundant element in Earth s crust, with a concentration of about 13 parts per million. This makes the element more common than other heavy metals such as thallium or uranium, but much less abundant than less well known elements such as niobium, neodymium, lanthanum, and gallium. 

Barium is the I4th most abundant element in Earth s crust. Its abundance is estimated to be about 0.05 percent. 

Carbon is the 17th most common element in Earth s crust. Its abundance has been estimated to be between 180 and 270 parts per million. It rarely occurs as a diamond or graphite. Both allotropes are formed in the earth over millions of years, when dead plant materials are squeezed together at very high temperamres. Diamonds are usually found hundreds or thousands of feet beneath the earth s surface. Africa has many diamond mines. 

Fluorine is an abundant element in Earth s crust, estimated at about 0.06 percent in the earth. That makes it about the 13th most common element in the crust. It is about as abundant as manganese or barium. 

The abundance of gold in Earth s crust is estimated to be about 0.005 parts per million. That makes it one of the 10 rarest elements in Earth s crust. Gold is thought to be much more common in the oceans. Some people believe as much as 70 million tons of gold are dissolved in seawater. They also think there may be another 10 billion tons on the bottom of the oceans. So far, however, no one has found a way to mine this gold. 

Hydrogen occurs on Earth primarily in the form of water. Every molecule of water (H2O) contains two hydrogen atoms and one oxygen atom. Hydrogen is also found in many rocks and minerals. Its abundance is estimated to be about 1,500 parts per million. That makes hydrogen the 10th most abundant element in Earth s crust. 

Iridium is one of the rarest elements in Earth s crust. Its abundance is estimated to be about two parts per billion. Interestingly, it is more abundant in other parts of the universe. Iron meteorites, for example, generally contain about 3 parts per million of iridium. Stony meteorites contain less iridium, about 0.64 parts per million. 

Nitrogen is a fairly common element in Earth s crust. It occurs primarily as nitrates and nitrites. Nitrogen is by far the most important element in Earth s atmosphere. It makes up 78.084 percent of the atmosphere. 

Osmium is very rare. Its abundance is thought to be about 0.001 parts per million (one part per billion). That places the element among the half dozen least abundant elements in Earth s crust. 

Oxygen is by far the most abundant element in Earth s crust. Nearly half of all the atoms in the earth are oxygen atoms. Oxygen also makes up about one-fifth of Earth s atmosphere. Nearly 90 percent of the weight of the oceans is due to oxygen. In addition, oxygen is thought to be the third most abundant element in the universe and in the solar system. 

Selenium is a very rare element. Scientists estimate its abundance at about 0.05 to 0.09 parts per million. It ranks among the 25 least common elements in Earth s crust. It is widely distributed throughout the crust. There is no ore from which it can be mined with profit. Instead, it is obtained as a by-product of mining other metals. It is now produced primarily from copper, iron, and lead ores. As of 2008, the major producers of selenium in the world were Japan, Belgium, and Canada. The actual amount of selenium produced in the United States was not reported as it is considered a trade secret. 

Silicon is the second most abundant element in Earth s crust, exceeded only by oxygen. Many rocks and minerals contain silicon. Examples include sand, quartz, clays, flint, amethyst, opal, mica, feldspar, garnet, tourmaline, asbestos, talc, zircon, emerald, and aquamarine. Silicon never occurs as a free element. It is always combined with one or more other elements as a compound. 

Silicon is the second most abundant element in Earth s crust. Its abundance is estimated to be about 27.6 percent of the crust. It ranks second only to oxygen. Some authorities believe that more than 97 percent of the crust is made of rocks that contain compounds of silicon and oxygen. 

Strontium is a relatively abundant element in Earth s crust. It ranks about 15th among the elements found on Earth. That makes it about as abundant as fluorine and its alkaline earth partner, barium. 

Thorium is a relatively abundant element in Earth s crust. Scientists estimate that the crust contains about 15 parts per million of the element. That fact is important from a commercial standpoint. It means that... 

Zirconium is a fairly common element in Earth s crust. Its abundance is estimated to be 150 to 230 parts per million. That places it just below carbon and sulfur among elements occurring in Earth s crust. The two most common ores of zirconium are zircon, or zirconium silicate... 

Aluminum is the third most abundant element in Earth s crust, exceeded only by oxygen and silicon. It is second to silicon as the most abundant metallic element. It is somewhat surprising, then, that aluminum was not discovered until relatively late in human history. Aluminum occurs naturally only in compounds, never as a pure metal. Removing aluminum from its compounds is quite difficult. An inexpensive method for producing pure aluminum was not developed until 1886. 

The most abundant elements in Earth s crust, silicon and oxygen, are usually found in silica, which can be melted and rapidly cooled to form glass. 

Aluminum manufacture Aluminum is the most abundant metallic element in Earth s crust, but until the late nineteenth century, aluminum metal was more precious than gold. Aluminum was expensive because no one knew how to purify it in large quantities. Instead, it was produced by a tedious and expensive small-scale process in which metallic sodium was used to reduce aluminum ions in molten aluminum fluoride to metallic aluminum. 

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