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platinummore about platinum

platinum

 

  4  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Platinum  \Plat"i*num\,  n.  [NL.,  fr  Sp  platina,  from  plata 
  silver,  LL  plata  a  thin  plate  of  metal.  See  {Plate},  and  cf 
  {Platina}.]  (Chem.) 
  A  metallic  element,  intermediate  in  value  between  silver  and 
  gold,  occurring  native  or  alloyed  with  other  metals,  also  as 
  the  platinum  arsenide  (sperrylite).  It  is  heavy  tin-white 
  metal  which  is  ductile  and  malleable,  but  very  infusible,  and 
  characterized  by  its  resistance  to  strong  chemical  reagents. 
  It  is  used  for  crucibles,  for  stills  for  sulphuric  acid, 
  rarely  for  coin,  and  in  the  form  of  foil  and  wire  for  many 
  purposes.  Specific  gravity  21.5.  Atomic  weight  194.3.  Symbol 
  Pt  Formerly  called  {platina}. 
 
  {Platinum  black}  (Chem.),  a  soft,  dull  black  powder, 
  consisting  of  finely  divided  metallic  platinum  obtained  by 
  reduction  and  precipitation  from  its  solutions.  It  absorbs 
  oxygen  to  a  high  degree,  and  is  employed  as  an  oxidizer. 
 
 
  {Platinum  lamp}  (Elec.),  a  kind  of  incandescent  lamp  of  which 
  the  luminous  medium  is  platinum.  See  under  {Incandescent}. 
 
 
  {Platinum  metals}  (Chem.),  the  group  of  metallic  elements 
  which  in  their  chemical  and  physical  properties  resemble 
  platinum.  These  consist  of  the  light  platinum  group  viz., 
  rhodium,  ruthenium,  and  palladium,  whose  specific 
  gravities  are  about  12;  and  the  heavy  platinum  group 
  viz.,  osmium,  iridium,  and  platinum,  whose  specific 
  gravities  are  over  21. 
 
  {Platinum  sponge}  (Chem.),  metallic  platinum  in  a  gray, 
  porous,  spongy  form  obtained  by  reducing  the  double 
  chloride  of  platinum  and  ammonium.  It  absorbs  oxygen, 
  hydrogen,  and  certain  other  gases,  to  a  high  degree,  and 
  is  employed  as  an  agent  in  oxidizing. 
 
  From  WordNet  r  1.6  [wn]: 
 
  platinum 
  n  :  a  heavy  precious  metallic  element;  gray-white  and  resistant 
  to  corroding;  occurs  in  some  nickel  and  copper  ores  and 
  is  also  found  native  in  some  deposits  [syn:  {Pt},  {atomic 
  number  78}] 
 
  From  U.S.  Gazetteer  (1990)  [gazetteer]: 
 
  Platinum,  AK  (city,  FIPS  61080) 
  Location:  58.97394  N,  161.72523  W 
  Population  (1990):  64  (45  housing  units) 
  Area:  115.4  sq  km  (land),  0.0  sq  km  (water) 
  Zip  code(s):  99651 
 
  From  Elements  database  20001107  [elements]: 
 
  platinum 
  Symbol:  Pt 
  Atomic  number:  78 
  Atomic  weight:  195.078 
  Attractive  greyish-white  metal.  When  pure,  it  is  malleable  and  ductile. 
  Does  not  oxidize  in  air,  insoluble  in  hydrochloric  and  nitric  acid. 
  Corroded  by  halogens,  cyandies  sulphur  and  alkalis.  {Hydrogen}  and 
  {oxygen}  react  explosively  in  the  presence  of  platinum.  There  are  six 
  stable  isotopes  and  three  radioisotopes,  the  most  stable  being  Pt-193 
  with  a  half-life  of  60  years.  Platinum  is  used  in  jewelry,  laboratory 
  equipment,  electrical  contacts,  dentistry,  and  anti-pollution  devices  in 
  cars.  PtCl2(NH3)2  is  used  to  treat  some  forms  of  cancer.  Platinum-{cobalt} 
  alloys  have  magnetic  properties.  It  is  also  used  in  the  definition  of 
  the  Standard  Hydrogen  Electrode.  Discovered  by  Antonio  de  Ulloa  in  South 
  America  in  1735.  The  name  comes  from  the  Spanish  word  platina  which  means 
  silver.  Platinum  metal  is  generally  not  a  health  concern  due  to  its 
  unreactivity  however  platinum  compounds  should  be  considered  highly 
  toxic.




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