Chemistry Nexus
by WebElements: the periodic table on the web
X-ray study of the alkali metals at low temperatures
Cold working of sodium metal converts body centred sodium metal to a mixture of a hexagonal form and body centred sodium at 5 K. The hexagonal from converts back to the body-centred form at 100-100 K.Cold working of lithium metal converts body centred lithium metal to a mixture of a hexagonal form and body centred lithium at 78 K.
Potassium, rubidium, and caesium retain their body centred structure after cooling.
WebElements December 24th, 2009
Posted In: Chemistry, Crystallography, Group 1 elements
Crystallographic Data 186. Lithium
Lithium at room temperature is body-centered cubic with 2 atoms per unit cell. The lattice constant for lithium metal is 3.51004 ± 0.00041 Å at 25°C. The theoretical density is 533 kg m–3 and the Li—Li bond distance for coordination number 8 is 3.0398 Å.1
SMILES: [Li]InChI: InChI=1/Li
References
WebElements December 24th, 2009
Posted In: Chemistry, Crystallography, Group 1 elements
Tags: Lithium
Crystallographic data for uranium mononitride
Uranium nitride, UN, is available through the direct reaction of uranium metal and nitrogen. The crystal structure is the NaCl type.
Abstract1
Crystal structure of uranium nitride, UN. The structure is face-centered cubic with a lattice constant of 4889 ± 0.001 Å at 26°C and sodium chloride type. The theoretical density is 14315 kg m–3, and the U—N bond distance for coordination number 6 is 2.4449 Å.
WebElements December 24th, 2009
Posted In: Chemistry, Crystallography
Approach to Mars
The European Space Agency’s Beagle 2 is approaching Mars for a landing (bouncy, but hopefully soft) on Christmas Day (will we hear “The Beagle has landed” !). Part of its mission is to look for chemical traces of life. One of the tests will be for methane in the martian atmosphere. Methane is a byproduct of life but will not last long in the Martian atmosphere, so a positive result would be interesting.
WebElements December 14th, 2009
Posted In: Analytical chemistry, Chemistry
Tags: Mars
Buildings Blocks of life found in deep space
An amino acid, one of the building blocks of life, has been spotted in deep space, signalling that alien life forms could indeed exist on other planets. If the find stands up to scutiny, it means that the sorts of chemistry needed to create life are not unique to Earth, verifying one of astrobiology’s cherished theories. This would add weight to the idea that life exists on other planets, or that molecules from outer space kick-started life on Earth.According
WebElements December 14th, 2009
Posted In: Analytical chemistry, Biological chemistry, Chemistry
Tags: glycine
Argon isotope mass measurements
A physicsweb.org article1 states that an international team working at the ISOLTRAP mass spectrometer at CERN has determined the masses of two isotopes of argon (32Ar and 33Ar) with the highest precision ever. This is important if you want “to place constraints on aspects of the weak interaction that are not included in the Standard Model”.
Abstract:1 masses of the short-lived radionuclides 32Ar (T1/2=98 ms) and 33Ar (T1/2=173 ms) have been determined with the Penning trap mass spectrometer ISOLTRAP.
WebElements December 9th, 2009
Posted In: Analytical chemistry, Chemistry
Does ET have the street lights on?
Scientists crossed a new frontier in exo-planet research just last year when, using the Hubble Space Telescope, they detected sodium by its characteristic orange colour in the atmosphere of a large alien world orbiting the star HD 209458. Perhaps we are seeing ETs street lighting from a distance?
Beginning in 2006, a new telescope, Kepler (approved recently by NASA) will monitor about 100,000 nearby stars, searching for the slight dimming that occurs when an orbiting planet blocks some of the parent star’s light.
WebElements December 8th, 2009
Posted In: Analytical chemistry, Atmospheric chemistry, Chemistry
Tags: Sodium
Hydrogen cars some time off yet
Many agree that replacing conventional petrol driven cars with hydrogen is a good idea provided the hydrogen does not originate in a process involving oil as the only product from hydrogen burning is water, rather than carbon dioxide.
However the road to hydrogen-powered vehicles will not be easy, industry experts state. Representatives of European and American car and energy companies at the National Hydrogen Association convention said hydrogen technology is feasible, but faces big challenges to become commercially viable.
WebElements March 21st, 2007
Posted In: Chemistry, Crystallography
Go to work on a terbium nitride buckyegg
An egg-shaped fullerene, or “buckyball egg” has been made and characterized by chemists in America at UC Davis (California), Virginia Tech, and Emory and Henry College in Virginia. They were trying to encapsulate terbium atoms within fullerenes but instead encapsulated terbium nitride within an egg-shaped fullerene. [http://dx.doi.org/10.1021/ja063636k]
The compound Tb3N@C84 was synthesized using an arc-discharge generator by vaporizing composite graphite rods containing a mixture of Tb4O7, graphite, and iron nitride as catalyst in a low-pressure He/N2atmosphere.
WebElements August 6th, 2006
Posted In: Chemistry, Crystallography, Nanoscience and nanotechnology
Carbonate minerals on Mars
A NASA press release indicates that NASA’s Spirit, the first of two Mars Exploration Rovers on the surface within Mars’ Gusev crater, has identified carbonate minerals “in the rover’s first survey of the site with its infrared sensing instrument, called the miniature thermal emission spectrometer or Mini-TES. Carbonates form in the presence of water, but it’s too early to tell whether the amounts detected come from interaction with water vapor in Mars’ atmosphere or are evidence of a watery local environment in the past, scientists emphasized.”
WebElements January 9th, 2004
Posted In: Analytical chemistry, Chemistry