PR
PR
Pr
Pr
Pr.
p.r.
Based on the Random House Dictionary, © Random House, Inc. 2012.
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| pr | |
| —abbreviation for , prs | |
| 1. | pair |
| 2. | paper |
| 3. | (in prescriptions) per rectum |
| 4. | power |
| [(sense 3) Latin: through the rectum; to be inserted into the anus] | |
| pr | |
| —the internet domain name for | |
| Puerto Rico | |
| Pr | |
| —the chemical symbol for | |
| praseodymium | |
| PR | |
| —abbreviation for | |
| 1. | proportional representation |
| 2. | public relations |
| 3. | Puerto Rico |
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Pr 1
The symbol for the element praseodymium.
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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| Pr
The symbol for praseodymium. |
praseodymium  (prā'zē-ō-dĭm'ē-əm) Pronunciation Key
Symbol Pr A soft, malleable, silvery metallic element of the lanthanide series that develops a green tarnish in air. It is used to add a yellow tint to glass and ceramics and to make the glass used in welding goggles. Atomic number 59; atomic weight 140.908; melting point 935°C; boiling point 3,127°C; specific gravity 6.8; valence 3, 4. See Periodic Table. |
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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| pr preferences |
Pr
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PR
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Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Pr
((Pr), chemical element, rare-earth metal of transition Group IIIb of the periodic table, used as the element in special alloys and, as its oxide, in glasses. Moderately soft, ductile, and malleable, this silvery metal rapidly displaces hydrogen from water and slowly reacts in air, developing a green oxide coating, which chips. For preservation, the metal must be sealed in a plastic covering or kept in mineral oil. Praseodymium was discovered in didymia, a mixture of several rare-earth oxides. From it, by repeated fractional crystallization of ammonium didymium nitrate, Carl Auer von Welsbach separated (1885) salts of the elements praseodymium (the green fraction) and neodymium. Praseodymium occurs in minerals such as monazite and bastnaesite and as one of the products of nuclear fission. Natural praseodymium is all stable isotope praseodymium-141. This element is commercially separated and purified by ion-exchange techniques; the reduction of the fluoride or chloride with calcium is one way in which the metal itself is prepared
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