| slovo | definícia |
polonium
(encz) | polonium,polonium n: Zdeněk Brož |
polonium
(czen) | polonium,poloniumn: Zdeněk Brož |
Polonium
(gcide) | Polonium \Po*lo"ni*um\ (p[-o]*l[=o]"n[i^]*[u^]m), n. [NL. So
named after Poland, in L. form Polonia, one of the
discoverers being a Pole.] (Chem.)
A radioactive chemical element, discovered by M. and MMe.
Curie in pitchblende, and originally called radium F. It
has atomic number 84 and an atomic weight of 210. It is a
very rare natural element, having an abundance in uranium
ores only 0.2% that of radium. It is closely related
chemically to bismuth. It emits only alpha rays, and has a
half-life of 138 days. It is thus more unstable than radium,
and a milligram of polonium emits as many alpha particles as
5 grams of radium. Twenty-seven isotopes are known, with
atomic masses from 192 to 218. At present a more practical
method of preparation than isolation from ores is the
preparation by neutron bombardment of bismuth in a nuclear
reactor, and it may be obtained commercially by users having
an appropriate permit. --[HBCF61]
[Webster 1913 Suppl. +PJC] |
polonium
(wn) | polonium
n 1: a radioactive metallic element that is similar to tellurium
and bismuth; occurs in uranium ores but can be produced by
bombarding bismuth with neutrons in a nuclear reactor [syn:
polonium, Po, atomic number 84] |
polonium
(elements) | polonium
Symbol: Po
Atomic number: 84
Atomic weight: (210)
Rare radioactive metallic element, belongs to group 16 of the periodic
table. Over 30 known isotopes exist, the most of all elements. Po-209
has
a half-life of 103 years. Possible uses in heating spacecraft.
Discovered
by Marie Curie in 1898 in a sample of pitchblende.
|
| | podobné slovo | definícia |
Polonium
(gcide) | Polonium \Po*lo"ni*um\ (p[-o]*l[=o]"n[i^]*[u^]m), n. [NL. So
named after Poland, in L. form Polonia, one of the
discoverers being a Pole.] (Chem.)
A radioactive chemical element, discovered by M. and MMe.
Curie in pitchblende, and originally called radium F. It
has atomic number 84 and an atomic weight of 210. It is a
very rare natural element, having an abundance in uranium
ores only 0.2% that of radium. It is closely related
chemically to bismuth. It emits only alpha rays, and has a
half-life of 138 days. It is thus more unstable than radium,
and a milligram of polonium emits as many alpha particles as
5 grams of radium. Twenty-seven isotopes are known, with
atomic masses from 192 to 218. At present a more practical
method of preparation than isolation from ores is the
preparation by neutron bombardment of bismuth in a nuclear
reactor, and it may be obtained commercially by users having
an appropriate permit. --[HBCF61]
[Webster 1913 Suppl. +PJC] |
|