Cretoxyrhina - Facts and Figures

Cretoxyrhina - Facts and Figures Name: Cretoxyrhina (Greek for Cretaceous jaws); pronounced creh-TOX-see-RYE-nah Habitat: Oceans worldwide Historical Period: Middle-late Cretaceous (100-80 million years ago) Size and Weight: About 25 feet long and 1,000-2,000 pounds Diet: Fish and other marine animals Distinguishing Characteristics: Medium size; sharp, enameled teeth About Cretoxyrhina Sometimes, a prehistoric shark just needs a catchy nickname to attract the attention of the general public. Thats what happened with the awkwardly named Cretoxyrhina (Cretaceous jaws), which surged in popularity a full century after its discovery when an enterprising paleontologist dubbed it the Ginsu Shark. (If youre of a certain age, you may remember the late-night TV commercials for the Ginsu Knife, which purportedly sliced through tin cans and tomatoes with equal ease.) Cretoxyrhina is one of the best-known of all prehistoric sharks. Its type fossil was discovered fairly early, in 1843 by the Swiss naturalist Louis Agassiz, and followed up 50 years later by the stunning discovery (in Kansas, by the paleontologist Charles H. Sternberg) of hundreds of teeth and part of a spinal column. Clearly, the Ginsu Shark was one of the top predators of the Cretaceous seas, able to hold its own against giant marine pliosaurs and mosasaurs that occupied the same ecological niches. (Still not convinced? Well, a Cretoxyrhina specimen has been discovered harboring undigested remnants of the giant Cretaceous fish Xiphactinus; then again, we also have evidence that Cretoxyrhina was preyed on by the even bigger marine reptile Tylosaurus!) At this point, you may be wondering how a Great White Shark-sized predator like Cretoxyrhina wound up fossilized in landlocked Kansas, of all places. Well, during the late Cretaceous period, much of the American midwest was covered by a shallow body of water, the Western Interior Sea, which teemed with fish, sharks, marine reptiles, and just about every other variety of Mesozoic marine creature. The two giant islands bordering this sea, Laramidia and Appalachia, were populated by dinosaurs, which unlike sharks went completely extinct by the start of the Cenozoic Era.

An Overview of Scandium (Sc or Element 21)

An Overview of Scandium (Sc or Element 21) Basic Facts Atomic Number: 21Symbol: ScAtomic Weight: 44.95591Discovery: Lars Nilson 1878 (Sweden)Electron Configuration: [Ar] 4s2 3d1Word Origin: Latin Scandia: ScandinaviaIsotopes: Scandium has 24 known isotopes ranging from Sc-38 to Sc-61. Sc-45 is the only stable isotope.Properties: Scandium has a melting point of 1541 Â °C, a boiling point of 2830 Â °C, a specific gravity of 2.989 (25 Â °C), and valence of 3. It is a silvery-white metal which develops a yellowish or pinkish cast when exposed to air. Scandium is a very light, relatively soft metal. Scandium reacts rapidly with many acids. The blue color of aquamarine is attributed to the presence of scandium.Sources: Scandium is found in the minerals thortveitite, euxenite, and gadolinite. It is also produced as a byproduct of uranium refinement.Uses: Scandium is used to make high-intensity lamps. Scandium iodide is added to mercury vapor lamps to produce a light source with a color resembling sunlight. The radioactive isotope Sc-46 is us ed as a tracer in refinery crackers for crude oil. Element Classification: Transition Metal Physical Data Density (g/cc): 2.99Melting Point (K): 1814Boiling Point (K): 3104Appearance: somewhat soft, silvery-white metalAtomic Radius (pm): 162Atomic Volume (cc/mol): 15.0Covalent Radius (pm): 144Ionic Radius: 72.3 (3e)Specific Heat (20Â °C J/g mol): 0.556Fusion Heat (kJ/mol): 15.8Evaporation Heat (kJ/mol): 332.7Pauling Negativity Number: 1.36First Ionizing Energy (kJ/mol): 630.8Oxidation States: 3Standard Reduction Potential: Sc3 e → Sc E0 -2.077 VLattice Structure: HexagonalLattice Constant (Ã…): 3.310Lattice C/A Ratio: 1.594CAS Registry Number: 7440-20-2 Trivia Scandium was named after Scandinavia. Chemist Lars Nilson was attempting to isolate the element ytterbium from the minerals euxenite and gadolinite when he discovered scandium. These minerals were primarily found in the Scandinavia region.Scandium is the transition metal with the lowest atomic number.The discovery of scandium filled a spot predicted by Mendeleevs periodic table. Scandium took the place of the placeholder element eka-boron.Most scandium compounds have scandium with the Sc3 ion.Scandium has an abundance in the Earths crust of 22 mg/kg (or parts per million).Scandium has an abundance in seawater of 6 x 10-7 mg/L (or parts per million).Scandium is more abundant on the Moon than on Earth. References: Los Alamos National Laboratory (2001) Crescent Chemical Company (2001)Langes Handbook of Chemistry (1952)CRC Handbook of Chemistry Physics (18th Ed.) International Atomic Energy Agency ENSDF database (Oct 2010)