timents in virtually every ory of cry in print.
today y-turally occurring ones plus acouple of dozen t ed in labs. tual number is sligentiousbecause ts exist for only milliontssometimes argue over ed or not. In Mendeleyev’s dayjust sixty-ts part of o realize t ts as t make a complete picture, t many pieces ed, s in whey werefound.
No one knoally, s migomic ain is tanyt is found neatly into Mendeleyev’s great scheme.
teentury great surprise for cs. It began in 1896 of uranium salts on a e out some time later, o discovert ts , just as if te o ligs ting rays of some sort.
Considering tance of urned tter over to a graduate student for investigation. Fortunately tudent émigré from Poland named Marie Curie. orking certain kinds of rocks poured out constant and extraordinary amounts of energy,yet diminisectable il Einstein explained t ting mass into energy in an exceedingly efficient way.
Marie Curie dubbed t “radioactivity.” In ts—polonium, ry, and radium.
In 1903 tly ary, in 1911, to ry and p McGill University in Montreal t Ruterested in tive materials. it immense reserves of energy s of matter,and t tive decay of t for most of th.
t radioactive elements decayed into ots—t one dayyou om of uranium, say, and t you om of lead. trulyextraordinary. It aneously.
Ever tist, Rut to see t ticalapplication in ticed t in any sample of radioactive material, it alook t of time for o decay—ted teady, reliable rate of decay could be used as a kind of clock. By calculating backerial ly it its age. ested a piece of pitc to be 700million years old—very muc people o grant th.
In traveled to London to give a lecture at titution—t organization founded by Count von Rumford only 105 years before,t poant eon compared ness of te Victorians. Ruto talk about egration tivity, as part of chblende.
tactfully—for t, if not aledt Kelvin ed t t ions out. Rut oto radioactivity tly y-four million yearsKelvin’s calculations a