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The programme opens with a consideration of the banding in the chlorides of elements of tne Na - Cl row of the periodic table. The use of election pair bonds to explain bonding in compounds like PC...1₅- and PF₅ leads to the assumed stability of a ten electron shell. The extension of this idea along the period suggest that there is no reason why noble gas fluorides like Ar F₂ should not exist. Prof. Haynes points out that such compounds had been suggested by Linus Pauling as long ago as 1932. Dr. Johnson takes up the story by explaining the thermodynamic logic behind the discovery in 1962 by Prof. Neil Bartlett of the first noble gas compound. Prof Haynes then talks to Prof. Bartlett about his discovery and its significance. The viewer is left with the problem of the nature of the bonding in compounds like Xenon difluorlde.
Metadata describing this Open University video programme
Item code: S25-; 07
First transmission date: 22-04-1972
Published: 1972
Rights Statement:
Restrictions on use:
Duration: 00:24:13
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Producer: Barrie Whatley
Contributors: Neil Bartlett; Len Haynes; David Johnson
Publisher: BBC Open University
Keyword(s): Chloride bonds; Electron pair bonds; Na-Cl row of periodic table; Noble gas fluorides; Prof.Neil Bartlett 1962; Xenon difluoride
Footage description: Len Haynes introduces the programme. He shows several still shots from the year 1962 (John Glenn, Telstar satellite at take-off, first commercial hover craft service, Russian ship with missiles bound for Cuba). Haynes then tells briefly about Neil Bartlett's 1962 experiment - the synthesis for the first time of XePtFG. David Johnson with chlorides of the elements of the third period. He explains that the stoichiometry of these chlorides could be accounted for by formulations in which every element attains the configuration of a noble gas, either ionic or covalent. Johnson then does am experiment which combine PCI₃ with chlorine to form a solid - PCI₅. Johnson then uses a diagram to show that if one assumes that shared electron bonds are assigned to each bond, then phosphorous has 10 not 8 electrons in its valence shell. Johnson looks at the same configuration using sodium (SF₄) and then with chlorine (ClF₃) Johnson then speculates that ArF₂, could be the next compound with this configuration. Len Haynes gives the historical background to the search for noble gas compounds. Shots of a letter, dated July 1933 from Linus Pauling to Fred Allen outlining his unsuccessful experiments. Haynes continues. David Johnson discusses Neil Bartlett's work which led to the synthesis of XePtF₆, the preparation of PtF₆O₂. Johnson compares X-ray powder photographs of this compound with one for KSbF₆. This suggests that O₂PtF₆ is a better configuration. He explains how Bartlett went on from there to consider the substitution of Xe+ for the O₂. Both have very similar ionization energies (12.1eV,12.2eV). Len Haynes interviews Neil Bartlett who tells the story of his discovery - the synthesis for the first time of a noble gas compound, XePtF₆, and the work which led up to it.
Master spool number: 6HT/70490
Production number: 00521_2189
Videofinder number: 1775
Available to public: no