The Carbon Chemistry and Crystal Structure of Diamonds

The Carbon Chemistry and Crystal Structure of Diamonds The word diamond is derived from the Greek word adamao, meaning I tame or I subdue or the related word adamas, which means hardest steel or hardest substance. Everyone knows diamonds are hard and beautiful, but did you know a diamond could be the oldest material you might own? While the rock in which diamonds are found may be 50 to 1,600 million years old, the diamonds themselves are approximately 3.3 billion years old. This discrepancy comes from the fact that the volcanic magma that solidifies into rock, where diamonds are found did not create them, but only transported the diamonds from the Earths mantle to the surface. Diamonds also may form under the high pressures and temperatures at the site of meteorite impacts. The diamonds formed during an impact may be relatively young, but some meteorites contain stardust - debris from the death of a star - which may include diamond crystals. One such meteorite is known to contain tiny diamonds over 5 billion years old. These diamonds are older than our solar system. Start with Carbon Understanding the chemistry of a diamond requires a basic knowledge of the element carbon. A neutral carbon atom has six protons and six neutrons in its nucleus, balanced by six electrons. The electron shell configuration of carbon is 1s22s22p2. Carbon has a valence of ​four since four electrons can be accepted to fill the 2p orbital. Diamond is made up of repeating units of carbon atoms joined to four other carbon atoms via the strongest chemical linkage, covalent bonds. Each carbon atom is in a rigid tetrahedral network where it is equidistant from its neighboring carbon atoms. The structural unit of diamond consists of eight atoms, fundamentally arranged in a cube. This network is very stable and rigid, which is why diamonds are so very hard and have a high melting point. Virtually all carbon on Earth comes from the stars. Studying the isotopic ratio of the carbon in a diamond makes it possible to trace the history of the carbon. For example, at the earths surface, the ratio of isotopes carbon-12 and carbon-13 is slightly different from that of stardust. Also, certain biological processes actively sort carbon isotopes according to mass, so the isotopic ratio of carbon that has been in living things is different from that of the Earth or the stars. Therefore, it is known that the carbon for most natural diamonds comes most recently from the mantle, but the carbon for a few diamonds is the recycled carbon of microorganisms, formed into diamonds by the earths crust via plate tectonics. Some minute diamonds that are generated by meteorites are from carbon available at the site of impact; some diamond crystals within meteorites are still fresh from the stars. Crystal Structure The crystal structure of a diamond is a face-centered cubic or FCC lattice. Each carbon atom joins four other carbon atoms in regular tetrahedrons (triangular prisms). Based on the cubic form and its highly symmetrical arrangement of atoms, diamond crystals can develop into several different shapes, known as crystal habits. The most common crystal habit is the eight-sided octahedron or diamond shape. Diamond crystals can also form cubes, dodecahedra, and combinations of these shapes. Except for two shape classes, these structures are manifestations of the cubic crystal system. One exception is the flat form called a macle, which is really a composite crystal, and the other exception is the class of etched crystals, which have rounded surfaces and may have elongated shapes. Real diamond crystals dont have completely smooth faces but may have raised or indented triangular growths called trigons. Diamonds have perfect cleavage in four different directions, meaning a diamond will separat e neatly along these directions rather than break in a jagged manner. The lines of cleavage result from the diamond crystal having fewer chemical bonds along the plane of its octahedral face than in other directions. Diamond cutters take advantage of lines of cleavage to facet gemstones. Graphite is only a few electron volts more stable than diamond, but the activation barrier for conversion requires almost as much energy as destroying the entire lattice and rebuilding it. Therefore, once the diamond is formed, it will not reconvert back to graphite because the barrier is too high. Diamonds are said to be metastable since they are kinetically rather than thermodynamically stable. Under the high pressure and temperature conditions needed to form a diamond, its form is actually more stable than graphite, and so over millions of years, carbonaceous deposits may slowly crystallize into diamonds.

Patron and Patronize

Patron and Patronize Patron and Patronize Patron and Patronize By Maeve Maddox Someone in my Facebook feed posted this about an aging celebrity who has recently published a book: â€Å"Don’t buy her books and don’t patron her movies.† I’d never seen patron used as a verb. Patronize is the verb commonly used to mean: â€Å"to frequent or support as a customer.† For example: I have patronized The Brown Derby since its inception and have always found the food to be second-to-none. A Web search turned up many examples of the unconventional use of patron in this sense. Here are two examples: The owner is very racist and I REFUSE to patron this place.   My wife and  I refuse to patron movie  theaters on Thanksgiving or Christmas.   Not surprisingly, the most common source of this nonstandard use of patron is social media. What did surprise me is that I found patron used as a verb in some British news sources. It was, however, used in the context of a well-known person agreeing to act as spokesman for a nonprofit enterprise: Lambeth Palace told The Times: â€Å"Since taking office in March this year, the Archbishop has received many kind invitations to patron a large variety of charities and good causes. –The Telegraph. Celebrity Piers Morgan to patron cat rescue centre –Bristol Post The prince has also agreed to patron Daresbury’s sister site at Harwell, Oxfordshire. –Runcorn and Widnes Weekly News. The noun patron derives from pater, the Latin word for father. In Latin society, a patron was a protector, someone who looked after the well-being of a former slave or other dependent. The feminine form was patrona. (A matrona was simply â€Å"a married woman.†) The earliest documentation in the OED of the verb patronize to mean, â€Å"to act as a patron towards† is dated 1593. The use of patron with this meaning has three 17th century citations, and one by Dickens in the 19th. (The use by Dickens is probably meant to be humorous: â€Å"Why am I to be Patroned and Patronessed as if the Patrons and Patronesses treated me?†) The first modern citation for patron used as a verb to mean â€Å"act as patron† is dated 1954, and this use is still rare even in Britain. In my unscientific browsing of British newspapers, I found that constructions like â€Å"agreed to serve as patron† outnumber constructions like â€Å"agreed to patron.† In addition to its meanings of â€Å"protection and support,† patronize has acquired a negative connotation. Human nature being what it is, the beneficial act of patronizing a good cause is often accompanied by an overt attitude that the donor is superior to the recipient. As a result, â€Å"to patronize† has become a synonym for â€Å"to condescend.† condescend (verb): to assume an air of superiority (as to one inferior or less fortunate) Here are some examples of patronize in this sense: How do you feel when people patronize your religion? Candidate In Iowa Makes Patronizing Offensive Comments About Women Voters Dont patronize me, she  said  heatedly. Im not one of your witless lady friends. Patron as a verb meaning, â€Å"serve as a spokesperson for a worthy cause† may catch on. Such use would serve to distinguish the act of serving as a spokesman from the less altruistic meanings of patronize. On the other hand, patronize is just one of many English words that have different meanings according to context. It’s the sort of thing one is expected to learn in English class. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Vocabulary category, check our popular posts, or choose a related post below:The Royal Order of Adjectives 30 Baseball Idioms30 Nautical Expressions