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
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