Metals

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

X-ray study of the alkali metals at low temperatures, Barrett, C. S. , Acta Crystallographica, 08/1956, Volume 9, Issue 8, p.671 - 677, (1956)

The Group 2 elements

The Group 2 elements are called the alkaline earth metals. The Group 2 elements are:

The electronic configuration of the elements all consist of two s-electrons outside an inner core of electron corresponding to the previous inert gas: the group configuration is therefore ns2.

Acknowledgements

I am indebted to a number of important contibutors, some of whom are detailed below.

Nearing Zero

WebElements™ has added Nearing Zero cartoons included by kind permission of Nick Kim, an example of a rare breed, a chemist who can produce excellent cartoons.

More contributors

I am grateful to the following experts:
  1. Gwyn Williams (Brookhaven National Laboratory, USA) who provided the electron binding energy data
  2. Dr Don Jenkins (University of Warwick, UK) who provided the lattice energy data
  3. Professor J.A. Kerr (University of Birmingham, UK) for the provision of the bond strengths of diatomic molecules data
  4. Professor Robin Harris (University of Durham, UK) who provided much of the NMR data, which are copyright 1996 IUPAC
  5. Professor Pekka Pyykkö (University of Helsinki, Finland) who provided the nuclear quadrupole moment data
  6. Barry Evans and Graham McElearney (University of Sheffield, UK) who provided some of the photographs of my fireworks. I am also pleased to acknowledge Steve Collier (Sheffield University Television) who filmed and digitized the video clips of my fireworks
  7. Malcolm Rathbone of Thessco, Sheffield, UK, who allowed me to photograph several elements on their site and for several pictures. And for putting on great parties over the years!
  8. Dr Andrew Goodfellow of Advent Research Materials Ltd, Oxford, UK, who allowed me to photograph samples of several elements so that you can see what they look like. Advent Research Materials are suppliers of high quality sample of metals (alloys, foils, sheets, wires, mesh, rods, tubes) for research and development and for industry. Further details on their web site

Other acknowledgements

During the preparation of an earlier version of this web site (prior to July 1997), the author had the benefit of the use of data and information compiled by Dr John Emsley for the 3rd edition of his book "The Elements". The author is also grateful to Professor Eric Scerri (University of California, Los Angeles, USA) for many perceptive comments over the years. The author is indebted to thousands of people, too many to list here, who have sent in corrections for WebElements™ and comments about WebElements™ since its launch in 1993. I'm still working my way through the correspondence (slowly)!

Self-cleaning titania nanotube hydrogen sensors

The Science Blog reports that researchers at Penn State in the USA are developing self-cleaning titania nanotube hydrogen sensors. The hydrogen sensors are titania nanotubes coated with a discontinuous layer of palladium. Hydrogen sensors are widely used in the chemical, petroleum and semiconductor industries. They are also used as diagnostic tools to monitor certain types of bacterial infections.

"The photocatalytic properties of titania nanotubes are so large - a factor of 100 times greater than any other form of titania - that sensor contaminants are efficiently removed with exposure to ultraviolet light, so that the sensors effectively recover or retain their original hydrogen sensitivity in real world application"

"By doping the titania nanotubes with trace amounts of different metals such as tin, gold, silver, copper, niobium and others, a wide variety of chemical sensors can be made. This doping does not alter the photocatalytic properties of the titania nanotubes" says Dr. Craig A. Grimes, associate professor of Electrical Engineering and Materials Science and Engineering.1

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Copyright 1993-2011 Mark Winter [The University of Sheffield and WebElements Ltd, UK]. All rights reserved.