If you walk into a garden in bloom and breathe deeply, you are likely to encounter great smells. In many cases, the molecules that bring those scents to your nose are terpenes.
The tertiary structure is the complete three-dimensional structure of a polypeptide chain. Many polypeptides fold into compact, globular structures in which amino acid residues that are distant from each other in primary structure come into close proximity in the folded structure.
Testosterone is a male sex hormone, one of a class of compounds known as androgens. Included in this group are testosterone, dihydrotestosterone, and androstenedione.
Thallium was discovered in 1861 by the British chemist Sir William Crookes.
Theoretical chemistry is the discipline that uses quantum mechanics, classical mechanics, and statistical mechanics to explain the structures and dynamics of chemical systems and to correlate, understand, and predict their thermodynamic and kinetic properties. Modern theoretical chemistry may be roughly divided into the study of chemical structure and the study of chemical dynamics.
Thermochemistry is the study of the heat released or absorbed as a result of chemical reactions. It is a branch of thermodynamics and is utilized by a wide range of scientists and engineers.
Thermodynamics is the science of heat and temperature and, in particular, of the laws governing the conversion of thermal energy into mechanical, electrical, or other forms of energy. It is a central branch of science that has important applications in chemistry, physics, biology, and engineering.
B vitamins are complex, water-soluble organic chemicals, often containing heterocyclic ring systems (containing one or more atoms other than carbon atoms); they cannot be synthesized by humans and are, therefore, required nutrients. Each of these vitamins is converted by the body into a coenzyme.
Thorium is a radioactive chemical element that belongs to the actinide series. Its ground state electronic configuration is [Rn]5f06d27s2.
Thulium is a silver-grey metal with a bright luster. Swedish chemist Per Theodor Cleve discovered the metal in 1879 while processing the ore erbia.
Tin makes up only about 0.001 percent of the earth's crust, but it was well known in the ancient world. Named after the Etruscan god Tinia, tin has the symbol Sn, which comes from the Latin word for tin, stannum, which is related to the word stagnum (dripping), because tin melts easily.
Titanium is a strong, lightweight, silver-white metal. It was discovered in 1791 by Reverend William Gregor, a British cleric who established its presence in the mineral menachanite.
Toxicity is the capacity of a substance to poison. Swiss physician Paracelsus (1493–1541) defined poison as follows: "What is there that is not a poison?
The term "transactinides" is used to refer to all elements beyond the actinides—that is, those elements with atomic numbers larger than 103. Lawrencium, with atomic number 103 and a full inner 5f electron shell, ends the actinide series.
The membrane of a cell is not only a border; it is also an interface. The most critical molecules involved in interface functioning are proteins that are embedded within the membrane.
Transmutation is the act of changing a substance, tangible or intangible, from one form or state into another. To the alchemists of old, this meant the conversion of one physical substance into another, particularly base metals such as lead into valuable silver and gold.
There are two different types of transport proteins: those that carry molecules to "distant" locations (within a cell or an organism), and those that serve as gateways, carrying molecules across otherwise impermeable membranes.
Triglycerides are the most common storage form of fat in many organisms. They are neutral lipid molecules created via the esterification of three fatty acids to a single glycerol molecule.
Tungsten is a metallic transition element in Period 6, Group 6 of the Periodic Table. It was first described in 1783 by Spanish brothers Juan Jose and Fausto de Elhuyar.
Uranium is a very dense, highly reactive, metallic element that has the highest atomic mass of the naturally occurring elements. Natural uranium consists of two long-lived radioactive isotopes: 238U (99.28%) and 235U (0.72%).
The valence bond (VB) theory of bonding was mainly developed by Walter Heitler and Fritz London in 1927, and later modified by Linus Pauling to take bond direction into account. The VB approach concentrates on forming bonds in localized orbitals between pairs of atoms, and hence retains the simple idea of Lewis structures and electron pairs.
Vanadium is a soft silver metal in group 5B of the Periodic Table. It was discovered in Mexican lead ore by Andreas Manuel del Rio in 1801.
Joseph John Thomson, always known as "J. J.," was born in Manchester, England, on December 18, 1856.
Alexander R. Todd was born in Glasgow on October 2, 1907.
The discovery of a new chemical element is a rare event; therefore, it is amazing that, in the space of only forty-two days, Morris Travers was involved in the discovery of not one but three new elements—krypton, neon, and xenon.
Harold Urey was a prolific scientist whose research interests included chemistry, astronomy, geology, and biology. Although he did important work on isotope applications and cosmochemistry, Urey is best remembered for his discovery of heavy hydrogen, or deuterium, for which he received the 1934 Nobel Prize in chemistry.
That atoms exist is a fact seemingly indisputable, but such was not always the case. In the early eighteenth century, when English chemist and physicist John Dalton made a case for his atomic theory, it was met with skepticism and spawned a vigorous debate that continued well into the twentieth century about whether or not atoms were real.
Johann Baptista van Helmont was a contemporary of the English philosopher Francis Bacon and the Italian astronomer Galileo Galilei. As with Galileo and his work, van Helmont's work in science brought him into conflict with religious authorities.