Technetium

Nalin Balan

NUCL 200

Paper due 02/07/97

TECHNETIUM

Atomic Number: 43

Atomic Symbol: Tc

Atomic Weight: (97)

Electron Configuration: -18-13-2

History, Properties and Uses:

(Gr. technetos, artificial) Element 43 was predicted on the basis of the periodi

c table,

and was erroneously reported as having been discovered in 1925, at which

time it was

named masurium. The element was actually discovered by Perrier and Segre

in Italy in

1937. It was found in a sample of molybdenum, which was bombarded by deut

erons in the Berkeley cyclotron, and which E. Lawrence sent to these investigators

.

Technetium was the first element to be produced artificially. Since its d

iscovery,

searches for the element in terrestrial material have been made without s

uccess. If it

does exist, the concentration must be very small. Technetium has been fou

nd in the

spectrum of S-, M-, and N-type stars, and its resence in stellar matter i

s leading to

new theories of the production of heavy elements in the stars.

English: water-NaCl phase diagram. Lide, CRC Handb...

English: CRC Handbook of Chemistry and Physics, 90...

English: CRC Handbook of Chemistry and Physics, 89...

Nineteen i

sotopes of

technetium, with atomic masses ranging from 90 to 108, are known. 97Tc ha

s a half-life of 2.6 x 10^6 years. 98Tc has a half-life of 4.2 x 10^6 years. The isomer

ic isotope

95mTc, with a half-life of 61 days, is useful for tracer work, as it prod

uces energetic

gamma rays. Technetium metal has been produced in kilogram quantities. Th

e metal

was first prepared by passing hydrogen gas at 1100C over Tc2S7. It is now

conveniently

prepared by the reduction of ammonium pertechnetate with hydrogen. Techne

tium is a

silvery-gray metal that tarnishes slowly in moist air. Until 1960, techne

tium was

available only in small amounts and the price was as high as $2800/g. It

is now

commercially available to holders of O.R.N.L. permits...