,transcriber's ,notes3 ,the following   
errors are noted1 but have not been     
corrected3      ,page #ag1 footnote3    
plutomium should be plutonium     ,page 
#h3 knowns should be knows  ,in element 
names1  represents subscripted numbers  
and  represents superscripted numbers4  
,readers may also refer to the ,,html   
version of the text1 in which super and 
subscripted numbers are represented     
visually4  ,italic emphasis is indicated
 by surrounding the word with           
underscores4  ,greek letters in the     
original text are marked in brackets1 e4
 g4 alpha or gamma4  ,table ,i 7,,the   
,,transuranium ,,elements7 has been     
moved from pages #ab-ac1 in the middle  
of the book1 to the end of the text4    
,a ,brief ,history     of     ,,element 
,,discovery1     ,,synthesis1 and       
,,analysis       ,glen ,w4 ,watson      
,september #aifc      ,illustration     
,,lawrence ,,radiation ,,laboratory     
,university of ,california     ,berkeley
 and ,livermore       ,operating under  

contract with the     ,united ,states   
,atomic ,energy ,commission             
,illustration3 ,radioactive elements3   
alpha particles from a speck of radium  
leave tracks on a photographic emulsion4
 7,occhialini and ,powell1 #aidg7     ,a
 ,,brief ,,history ,,of ,,element       
,,discovery1 ,,synthesis1 ,,and         
,,analysis   ,it is well known that the 
number of elements has grown from four  
in the days of the ,greeks to #ajc at   
present1 but the change in methods      
needed for their discovery is not so    
well known4 ,up until #aici1 only #hh   
naturally occurring elements had been   
discovered4 ,it took a dramatic modern  
technique 7based on ,ernest ,o4         
,lawrence's ,nobel-prize-winning atom   
smasher1 the cyclotron7 to synthesize   
the most recently discovered elements4  
,most of these recent discoveries are   
directly attributed to scientists       
working under the ,atomic ,energy       
,commission at the ,university of       
,california's ,radiation ,laboratory at 

,berkeley4  ,but it is apparent that our
 present knowledge of the elements      
stretches back into history3 back to    
,england's ,ernest ,rutherford1 who in  
#aiai proved that1 occasionally1 when an
 alpha particle from radium strikes a   
nitrogen atom1 either a proton or a     
hydrogen nucleus is ejected2 to the     
,dane ,niels ,bohr and his #aiac idea of
 electron orbits2 to a once unknown     
,swiss patent clerk1 ,albert ,einstein1 
and his now famous theories2 to         
,poland's ,marie ,curie who1 in #ahih1  
with her ,french husband ,pierre        
laboriously isolated polonium and       
radium2 back to the ,french scientist   
,h4 ,a4 ,becquerel1 who first discovered
 something he called a spontaneous      
emission of penetrating rays from       
certain salts of uranium2 to the ,german
 physicist ,w4 ,k4 ,roentgen and his    
discovery of x rays in #ahie2 and back  
still further4  ,during this passage of 
scientific history1 the very idea of    
element has undergone several great     

changes4  ,the early ,greeks suggested  
earth1 air1 fire1 and water as being the
 essential material from which all      
others were made4 ,aristotle considered 
these as being combinations of four     
properties3 hot1 cold1 dry1 and moist   
7see ,fig4 #a74  ,illustration3 ,fig4   
#a4 ,the elements as proposed by the    
early ,greeks4  ,later1 a fifth essence1
 ether1 the building material of the    
heavenly bodies was added4  ,paracelsus 
7#adic-aeda7 introduced the three       
alchemical symbols salt1 sulfur1 and    
mercury4 ,sulfur was the principle of   
combustability1 salt the fixed part left
 after burning 7calcination71 and       
mercury the essential part of all       
metals4 ,for example1 gold and silver   
were supposedly different combinations  
of sulfur and mercury4  ,robert ,boyle  
in his ,sceptical ,chymist 7#affa7 first
 defined the word element in the sense  
which it retained until the discovery of
 radioactivity 7#ahif71 namely1 a form  
of matter that could not be split into  

simpler forms4  ,the first discovery of 
a true element in historical time was   
that of phosphorus by ,dr4 ,brand of    
,hamburg1 in #affi4 ,brand kept his     
process secret1 but1 as in modern times1
 knowledge of the element's existence   
was sufficient to let others1 like      
,kunkel and ,boyle in ,england1 succeed 
independently in isolating it shortly   
afterward4  ,as in our atomic age1 a    
delicate balance was made between the   
light-giving 7desirable7 and heat-giving
 7feared7 powers of a discovery4 ,an    
early experimenter was at first         
delighted with the white1 waxy substance
 that glowed so charmingly in the dark  
of his laboratory1 but later wrote1 ,i  
am not making it any more for much harm 
may come of it4  ,robert ,boyle wrote in
 #afhj of phosphorus1 ,it shone so      
briskly and lookt so oddly that the     
sight was extreamly pleasing1 having in 
it a mixture of strangeness1 beauty and 
frightfulness4  ,these words describe   
almost exactly the impressions of eye   

witnesses of the first atom bomb test at
 ,alamagordo1 ,new ,mexico1 ,july #af1  
#aide4  ,for the next two and           
three-quarters centuries the chemists   
had much fun and some fame discovering  
new elements4 ,frequently there was a   
long interval between discovery and     
recognition4 ,thus ,scheele made        
chlorine in #aggd by the action of black
 manganese 7manganese dioxide7 on       
concentrated muriatic acid 7hydrochloric
 acid71 but it was not recognized as an 
element till the work of ,davy in #ahaj4
  ,occasionally the development of a new
 technique would lead to the easy       
discovery of a whole group of new       
elements4 ,thus ,davy1 starting in      
#ahjg1 applied the method of            
electrolysis1 using a development of    
,volta's pile as a source of current2 in
 a short time he discovered aluminum1   
barium1 boron1 calcium1 magnesium1      
potassium1 sodium1 and strontium4  ,the 
invention of the spectroscope by ,bunsen
 and ,kirchhoff in #ahei provided a new 

tool which could establish the purity of
 substances already known and lead to   
the discovery of others4 ,thus1 helium  
was discovered in the sun's spectrum by 
,jansen and isolated from uranite by    
,ramsay in #ahie4  ,the discovery of    
radioactivity by ,becquerel in #ahif    
7touched off by ,roentgen's discovery of
 x rays the year before7 gave an even   
more sensitive method of detecting the  
presence or absence of certain kinds of 
matter4 ,it is well known that ,pierre  
and ,marie ,curie used this new-found   
radioactivity to identify the new       
elements polonium and radium4 ,compounds
 of these new elements were obtained by 
patient fractional recrystallization of 
their salts4  ,the explanation of       
radioactivity led to the discovery of   
isotopes by ,rutherford and ,soddy in   
#aiad1 and with this discovery a        
revision of our idea of elements became 
necessary4 ,since ,boyle1 it had been   
assumed that all atoms of the individual
 elements were identical and unlike any 

others1 and could not be changed into   
anything simpler4 ,now it became evident
 that the atoms of radioactive elements 
were constantly changing into other     
elements1 thereby releasing very large  
amounts of energy1 and that many        
different forms of the same element     
7lead was the first studied7 were       
possible4 ,we now think of an element as
 a form of matter in which all atoms    
have the same nuclear charge4  ,the     
human mind has always sought order and  
simplification of the external world2 in
 chemistry the fruitful classifications 
were ,dobereiner's ,triads 7#ahbi71     
,newland's law of octaves 7#ahfe71 and  
,mendeleev's periodic law 7#ahfi74 ,the 
chart expressing this periodic law      
seemed to indicate the maximum extent of
 the elements and gave good hints where 
to look for and the probable properties 
of the remaining ones 7see ,fig4 #b74   
,by #aibe1 all but four of the slots in 
the #ib-place file had been filled4 ,the
 vacancies were at #dc1 #fa1 #he1 and   

#hg4  ,illustration3 ,fig4 #b4 ,periodic
 chart of the elements 7#aifc7  ,workers
 using traditional analytical techniques
 continued to search for these elements1
 but their efforts were foredoomed to   
failure4 ,none of the nuclei of the     
isotopes of elements #dc1 #fa1 #he1 and 
#hg are stable2 hence weighable         
quantities of them do not exist in      
nature1 and new techniques had to be    
developed before we could really say we 
had discovered them4  ,in #aiai1        
,rutherford accomplished scientifically 
what medieval alchemists had failed to  
do with magic experiments and other less
 sophisticated techniques4 ,it wasn't   
gold 7the goal of the alchemists7 he    
found but something more valuable with  
even greater potential for good and     
evil3 a method of transmuting one       
element into another4 ,by bombarding    
nitrogen nuclei with alpha particles    
from radium1 he found that nitrogen was 
changed into oxygen4  ,the process for  
radioactive transmutation is somewhat   

like a common chemical reaction4 ,an    
alpha particle1 which has the same      
charge 7#b7 and atomic mass 7#d7 as a   
helium nucleus1 penetrates the repulsive
 forces of the nitrogen nucleus and     
deposits one proton and one neutron2    
this changes the nitrogen atom into an  
oxygen atom4 ,the reaction is written   
#g,n#ad  #b;,he#d -- #a;,h#a  #h,o#ag4  
,the number at the lower left of each   
element symbol in the above reaction is 
the proton number4 ,this number         
determines the basic chemical identity  
of an atom1 and it is this number       
scientists must change before one       
element can be transformed into another4
 ,the common way to accomplish this     
artificially is by bombarding nuclei    
with nuclear projectiles4  ,rutherford  
used naturally occurring alpha particles
 from radium as his projectiles because 
they were the most effective he could   
then find4 ,but these natural alpha     
particles have several drawbacks3 they  
are positively charged1 like the nucleus

 itself1 and are therefore more or less 
repulsed depending on the proton number 
of the element being bombarded2 they do 
not move fast enough to penetrate the   
nuclei of heavier elements 7those with  
many protons72 and1 for various other   
reasons 7some of them unexplained71 are 
inefficient in breaking up the nucleus4 
,it is estimated that only #a out of    
#cjj1jjj of these alpha particles will  
react with nitrogen4  ,physicists       
immediately began the search for        
artificial means to accelerate a wider  
variety of nuclear particles to high    
energies4  ,protons1 because they have a
 #a charge rather than the #b charge of 
the alpha particles1 are repulsed less  
strongly by the positive charge on the  
nucleus1 and are therefore more useful  
as bombarding projectiles4 ,in #aibi1   
,e4 ,t4 ,s4 ,walton and ,j4 ,d4         
,cockcroft passed an electric discharge 
through hydrogen gas1 thereby removing  
electrons from the hydrogen atom2 this  
left a beam of protons 7i4 e41 hydrogen 

ions71 which was then accelerated by    
high voltages4 ,this ,cockcroft-,walton 
voltage multiplier accelerated the      
protons to fairly high energies 7about  
#hjj1jjj electron volts71 but the       
protons still had a plus charge and     
their energies were still not high      
enough to overcome the repulsive forces 
7,coulombic repulsion7 of the heavier   
nuclei4  ,a later development1 the ,van 
de ,graaff electrostatic generator1     
produced a beam of hydrogen ions and    
other positively charged ions1 and      
electrons at even higher energies4 ,an  
early model of the linear accelerator   
also gave a beam of heavy positive ions 
at high energies4 ,these were the next  
two instruments devised in the search   
for efficient bombarding projectiles4   
,however1 the impasse continued3 neither
 instrument allowed scientists to crack 
the nuclei of the heavier elements4     
,ernest ,o4 ,lawrence's cyclotron1 built
 in #aica1 was the first device capable 
of accelerating positive ions to the    

very high energies needed4 ,its basic   
principle of operation is not difficult 
to understand4 ,a charged particle      
accelerated in a cyclotron is analogous 
to a ball being whirled on a string     
fastened to the top of a pole4 ,a       
negative electric field attracts the    
positively charged particle 7ball7      
towards it and then switches off until  
the particle swings halfway around2 the 
field then becomes negative in front of 
the particle again1 and again attracts  
it4 ,as the particle moves faster and   
faster it spirals outward in an ever    
increasing circle1 something like a     
tether ball unwinding from a pole4 ,the 
energies achieved would have seemed     
fantastic to earlier scientists4 ,the   
,bevatron1 a modern offspring of the    
first cyclotron1 accelerates protons to 
#ii4ac the speed of light1 thereby      
giving them #f4b billion electron volts 
7,be,v74  ,another instrument1 the      
heavy-ion linear accelerator 7,hilac71  
accelerates ions as heavy as neon to    

about #ae the speed of light4 ,it is    
called a linear accelerator because it  
accelerates particles in a straight     
line4 ,stanford ,university is currently
 7#aifc7 in the process of building a   
linear accelerator approximately two    
miles long which will accelerate charged
 particles to #ii4i the speed of light4 
,but highly accelerated charged         
particles did not solve all of science's
 questions about the inner workings of  
the nucleus4  ,in #aicb1 during the     
early search for more efficient ways to 
bombard nuclei1 ,james ,chadwick        
discovered the neutron4 ,this particle1 
which is neutral in charge and is       
approximately the same mass as a proton1
 has the remarkable quality of          
efficiently producing nuclear reactions 
even at very low energies4 ,no one      
exactly knowns why4 ,at low energies1   
protons1 alpha particles1 or other      
charged particles do not interact with  
nuclei because they cannot penetrate the
 electrostatic energy barriers4 ,for    

example1 slow positive particles pick up
 electrons1 become neutral1 and lose    
their ability to cause nuclear          
transformations4 ,slow neutrons1 on the 
other hand1 can enter nearly all atomic 
nuclei and induce fission of certain of 
the heavier ones4 ,it is1 in fact1 these
 properties of the neutron which have   
made possible the utilization of atomic 
energy4  ,with these tools1 researchers 
were not long in accurately identifying 
the missing elements #dc1 #fa1 #he1 and 
#hg and more--indeed1 the list of new   
elements1 isotopes1 and particles now   
seems endless4  ,element #dc was made   
for the first time as a result of       
bombarding molybdenum with deuterons in 
the ,berkeley cyclotron4 ,the chemical  
work of identifying the element was done
 by ,emilio ,segr and others then       
working at ,palermo1 ,sicily1 and they  
chose to call it technetium1 because it 
was the element first made by artificial
 technical methods4  ,element #fa was   
made for the first time from the fission

 disintegration products of uranium in  
the ,clinton 7,oak ,ridge7 reactor4     
,marinsky and ,glendenin1 who did the   
chemical work of identification1 chose  
to call it promethium because they      
wished to point out that just as        
,prometheus stole fire 7a great force   
for good or evil7 from the hidden       
storehouse of the gods and presented it 
to man1 so their newly assembled reactor
 delivered to mankind an even greater   
force1 nuclear energy4  ,element #he is 
called astatine1 from the ,greek        
astatos1 meaning unstable1 because      
astatine is unstable 7of course all     
other elements having a nuclear charge  
number greater than #hd are unstable1   
too74 ,astatine was first made at       
,berkeley by bombarding bismuth with    
alpha particles1 which produced astatine
 and released two neutrons4 ,the element
 has since been found in nature as a    
small constituent of the natural decay  
of actinium4  ,the last of the original 
#ib elements to be discovered was       

element #hg1 francium4 ,it was          
identified in #aici by ,french scientist
 ,marguerite ,perey4  ,children have a  
game in which they pile blocks up to see
 how high they can go before they topple
 over4 ,in medieval times1 petty rulers 
in their ,italian states vied with one  
another to see who could build the      
tallest tower4 ,some beautiful results  
of this game still remain in ,florence1 
,siena1 and other ,italian hill cities4 
,currently1 ,americans vie in a similar 
way with the wheelbase and overall      
length of their cars4 ,after #aicd1 the 
game among scientists took the form of  
seeing who could extend the length of   
the periodic system of the elements2 as 
with medieval towers1 it was ,italy that
 again began with the most enthusiasm   
and activity under the leadership of    
,enrico ,fermi4  ,merely adding neutrons
 would not be enough2 that would make   
only a heavier isotope of the already   
known heaviest elements1 uranium4       
,however1 if the incoming neutron caused

 some rearrangement within the nucleus  
and if it were accompanied by expulsion 
of electrons1 that would make a new     
element4 ,trials by ,fermi and his      
co-workers with various elements led to 
unmistakeable evidence of the expulsion 
of electrons 7beta activity7 with at    
least four different rates of decay     
7half-lives74 ,claims were advanced for 
the creation of elements #ic and #id and
 possibly further 7the transuranium     
elements1 ,table ,i74 ,much difficulty  
was experienced1 however1 in proving    
that the activity really was due to the 
formation of elements #ic and #id4 ,as  
more people became interested and       
extended the scope of the experiments1  
the picture became more confused rather 
than clarified4 ,careful studies soon   
showed that the activities did not decay
 logarithmically--which means that they 
were caused by mixtures1 not individual 
pure substances--and the original four  
activities reported by ,fermi grew to at
 least nine4  ,as a matter of fact1 the 

way out of the difficulty had been      
indicated soon after ,fermi's original  
announcement4 ,dr4 ,ida ,noddack pointed
 out that no one had searched among the 
products of ,fermi's experiment for     
elements lighter than lead1 but no one  
paid any attention to her suggestion at 
the time4 ,the matter was finally       
cleared up by ,dr4 ,otto ,hahn and ,f4  
,strassmann4 ,they were able to show    
that instead of uranium having small    
pieces like helium nuclei1 fast         
electrons1 and super-hard x-rays1       
knocked off as expected1 the atom had   
split into two roughly equal pieces1    
together with some excess neutrons4     
,this process is called nuclear fission4
 ,the two large pieces were unstable and
 decayed further with the loss of       
electrons1 hence the beta activity4     
,this process is so complicated that    
there are not1 as originally reported1  
only four half-lives1 but at least #bjj 
different varieties of at least #ce     
different elements4 ,the discovery of   

fission attended by the release of      
enormous amounts of energy led to       
feverish activity on the part of        
physicists and chemists everywhere in   
the world4 ,in ,june #aidj1 ,mc,millan  
and ,abelson presented definite proof   
that element #ic had been found in      
uranium penetrated by neutrons during   
deuteron bombardment in the cyclotron at
 the ,university of ,california         
,radiation ,laboratory4  ,the           
,california scientists called the newly 
discovered element neptunium1 because it
 lies beyond the element uranium just as
 the planet ,neptune lies beyond        
,uranus4 ,the particular isotope formed 
in those first experiments was          
#ic,np#bci2 this is read neptunium      
having a nuclear charge of #ic and an   
atomic mass number of #bci4 ,it has a   
half-life of #b4c days1 during which it 
gives up another electron 7beta         
particle7 and becomes element #id1 or   
plutonium 7so called after ,pluto1 the  
next planet beyond ,neptune74 ,this     

particular form of plutonium            
7#id,pu#bci7 has such a long half-life  
7#bd1jjj years7 that it could not be    
detected4 ,the first isotope of element 
#id to be discovered was ,pu#bch1 made  
by direct deuteron bombardment in the   
,berkeley #fj-;inch cyclotron by        
,radiation ,laboratory scientists       
,seaborg1 ,mc,millan1 ,kennedy1 and     
,wahl2 it had an alpha-decay half-life  
of #hf4d years1 which gave it sufficient
 radioactivity so that its chemistry    
could be studied4  ,having found these  
chemical properties in ,pu#bch1         
experimenters knew #id,pu#bci would     
behave similarly4 ,it was soon shown    
that the nucleus of #id,pu#bci would    
undergo fission in the same way as      
#ib,u#bce when bombarded with slow      
neutrons and that it could be produced  
in the newly assembled atomic pile4     
,researchers wished to learn as much as 
possible about its chemistry2 therefore1
 during the summer of #aidb two large   
cyclotrons at ,st4 ,louis and ,berkeley 

bombarded hundreds of pounds of uranium 
almost continuously4 ,this resulted in  
the formation of #bjj micrograms of     
plutonium4 ,from this small amount1     
enough of the chemical properties of the
 element were learned to permit correct 
design of the huge plutonium-recovery   
plant at ,hanford1 ,washington4 ,in the 
course of these investigations1 balances
 that would weigh up to #aj4e mg with a 
sensitivity of #j4jb microgram were     
developed4 ,the test tubes and beakers  
used had internal diameters of #j4a to  
#a mm and could measure volumes of      
#a_/aj to #a_/aj1jjj ml with an accuracy
 of #a4 ,the fact that there was no     
intermediate stage of experimentation1  
but a direct scale-up at ,hanford of ten
 billion times1 required truly heroic   
skill and courage4  ,by #aidd sufficient
 plutonium was available from uranium   
piles 7reactors7 so that it was         
available as target material for        
cyclotrons4 ,at ,berkeley it was        
bombarded with #cb-,me,v doubly charged 

helium ions1 and the following reactions
 took place3      #id,pu#bci 7alpha1 n7 
#if;,cm#bdb alpha _/ #aej days --       
#id,pu#bch4  ,this is to be read3       
plutonium having an atomic number of #id
 7#id positively charged protons in the 
nucleus7 and a mass number of #bci 7the 
whole atom weighs approximately #bci    
times as much as a proton71 when        
bombarded with alpha particles          
7positively charged helium nuclei7      
reacts to give off a neutron and a new  
element1 curium1 that has atomic number 
#if and mass number #bdb4 ,this gives   
off alpha particles at such a rate that 
half of it has decomposed in #aej days1 
leaving plutonium with atomic number #id
 and mass number #bch4 ,the             
radiochemical work leading to the       
isolation and identification of the     
atoms of element #if was done at the    
metallurgical laboratory of the         
,university of ,chicago4  ,the intense  
neutron flux available in modern        
reactors led to a new element1 americium

 7,am71 as follows3      #id,pu#bci 7n1 
gamma7 #id,pu#bdj 7n1 gamma7 #id,pu#bda 
beta             -- #ie;,am#bda4  ,the  
notation 7n1 gamma7 means that the      
plutonium absorbs a neutron and gives   
off some energy in the form of gamma    
rays 7very hard x rays72 it first forms 
#id,pu#bdj and then #id,pu#bda1 which is
 unstable and gives off fast electrons  
7beta71 leaving #ie;,am#bda4  ,berkelium
 and californium1 elements #ig and #ih1 
were produced at the ,university of     
,california by methods analogous to that
 used for curium1 as shown in the       
following equations3      #ie;,am#bdj   
alpha -- #ig;,bk#bdc  #jn#a1  and       
#if;,cm#bda  alpha -- #ih;,cf#bdd       
#jn#a4  ,the next two elements1         
einsteinium 7#ii;,es7 and fermium       
7#ajj;,fm71 were originally found in the
 debris from the thermonuclear device   
,mike1 which was detonated on ,eniwetok 
atoll ,november #aieb4 7,this method of 
creating new substances is somewhat more
 extravagant than the mythical ,chinese 

method of burning down a building to get
 a roast pig47  ,these elements have    
since been made in nuclear reactors and 
by bombardment4 ,this time the bullet   
was ,n#ad stripped of electrons till it 
had a charge of #f1 and the target was  
plutonium4  ,researchers at the         
,university of ,california used new     
techniques in forming and identifying   
element #aja1 mendelevium4 ,a very thin 
layer of #ii;,es#bec was electroplated  
onto a thin gold foil and was then      
bombarded1 from behind the layer1 with  
#da-,me,v alpha particles4 ,unchanged   
#ii;,es#bec stayed on the gold1 but     
those atoms hit by alpha particles were 
knocked off and deposited on a catcher  
gold foil1 which was then dissolved and 
analyzed 7,fig4 #c74 ,this freed the new
 element from most of the very reactive 
parent substances1 so that analysis was 
easier4 ,even so1 the radioactivity was 
so weak that the new element was        
identified one atom at a time2 this is  
possible because its daughter element1  

fermium1 spontaneously fissions and     
releases energy in greater bursts than  
any possible contaminant4               
,illustration3 ,fig4 #c4 ,the production
 of mendelevium4  ,in #aieg1 in         
,stockholm1 element #ajb was reported   
found by an international team of       
scientists 7who called it nobelium71 but
 diligent and extensive research failed 
to duplicate the ,stockholm findings4   
,however1 a still newer technique       
developed at ,berkeley showed the       
footprints--if not the living           
presence--of #ajb 7see ,fig4 #d74 ,the  
rare isotope curium-#bdf is coated on a 
small piece of nickel foil1 enclosed in 
a helium-filled container1 and placed in
 the heavy-ion linear accelerator       
7,hilac7 beam4 ,positively charged atoms
 of element #ajb are knocked off the    
foil by the beam1 which is of carbon-#ab
 or carbon-#ac nuclei1 and are deposited
 on a negatively charged conveyor apron4
 ,but element #ajb doesn't live long    
enough to be actually measured4 ,as it  

decays1 its daughter product1           
#ajj;,fm#bej1 is attracted onto a       
charged aluminum foil where it can be   
analyzed4 ,the researchers have decided 
that the hen really did come first3 they
 have the egg2 therefore the hen must   
have existed4 ,by measuring the time    
distance between target and daughter    
product1 they figure that the hen-mother
 7element #ajb7 must have a half-life of
 three seconds4  ,illustration3 ,fig4   
#d4 ,the experimental arrangement used  
in the discovery of element #ajb4  ,in  
an experiment completed in #aifa1       
researchers at the ,university of       
,california at ,berkeley unearthed      
similar footprints belonging to element 
#ajc 7named lawrencium in honor of      
,nobel prizewinner ,ernest ,o4          
,lawrence74 ,they found that the        
bombardment of californium with boron   
ions released alpha particles which had 
an energy of #h4f ,me,v and decayed with
 a half-life of #h  #b seconds4 ,these  
particles can only be produced by       

element #ajc1 which1 according to one   
scientific theory1 is a type of dinosaur
 of matter that died out a few weeks    
after creation of the universe4  ,the   
half-life of lawrencium 7,lw7 is about  
#h seconds1 and its mass number is      
thought to be #beg1 although further    
research is required to establish this  
conclusively4  ,research on lawrencium  
is complicated4 ,its total alpha        
activity amounts to barely a few counts 
per hour4 ,and1 since scientists had the
 alpha-particle footprints only and not 
the beast itself1 the complications     
increased4 ,therefore no direct chemical
 techniques could be used1 and element  
#ajc was the first to be discovered     
solely by nuclear methods4,a  ,for many 
years the periodic system was considered
 closed at #ib4 ,it has now been        
extended by at least eleven places      
7,table ,i71 and one of the extensions  
7plutonium7 has been made in truckload  
lots4 ,its production and use affect the
 life of everyone in the ,united ,states

 and most of the world4  ,surely the end
 is again in sight1 at least for        
ordinary matter1 although persistent    
scientists may shift their search to the
 other-world anti particles4 ,these1    
too1 will call for very special         
techniques for detection of their       
fleeting presence4  ,early enthusiastic 
researchers complained that a man's life
 was not long enough to let him do all  
the work he would like on an element4   
,the situation has now reached a state  
of equilibrium2 neither man nor element 
lives long enough to permit all the     
desired work4  ,a ,in ,august #aifd     
,russian scientists claimed that they   
created element #ajd with a half-life of
 about #j4c seconds by bombarding       
plutomium with accelerated neon-#bb     
ions4   ,table ,i4 ,,the ,,transuranium 
,,elements       ,element    ,name      
7,symbol7     ,mass     ,year           
,discovered2 by whom2                   
,number          where2 how             
----------------------------------------

--------------------------------        
#ic     ,neptunium 7,np7      #bch      
#aidj2 ,e4 ,m4 ,mc,millan1 ,p4 ,h4      
,abelson2 ,university of ,california    
at ,berkeley2 slow-neutron              
bombardment of ,u#bch in the            
#fj-;inch cyclotron4                    
----------------------------------------
--------------------------------        
#id     ,plutonium 7,pu7      #bch      
#aida2 ,j4 ,w4 ,kennedy1 ,e4 ,m4        
,mc,millan1 ,g4 ,t4 ,seaborg1 and ,a4   
,c4                                     
,wahl2 ,university of ,california at    
,berkeley2 #af-,me,v deuteron           
bombardment of ,u#bch in the            
#fj-;inch cyclotron4                    
7,pu7      #bci    ,pu#bci2 the         
fissionable isotope                     
of plutonium1 was also discovered       
in #aida by ,j4 ,w4 ,kennedy1 ,g4 ,t4   
,seaborg1 ,e4 ,segr and ,a4 ,c4 ,wahl2  
,university of ,california at           
,berkeley2 slow-neutron bombardment     
of ,u#bch in the #fj-;inch              

cyclotron4                              
----------------------------------------
--------------------------------        
#ie     ,americium 7,am7      #bda      
#aidd-de2 ,berkeley scientists ,a4      
,ghiorso1 ,r4 ,a4 ,james1 ,l4 ,o4       
,morgan1 and ,g4 ,t4 ,seaborg at the    
,university of ,chicago2 intense        
neutron bombardment of plutonium        
in nuclear reactors4                    
----------------------------------------
--------------------------------        
#if     ,curium 7,cm7         #bdb      
#aide2 ,berkeley scientists ,a4         
,ghiorso1 ,r4 ,a4 ,james1 and ,g4 ,t4   
,seaborg at the ,university of          
,chicago2 bombardment of ,pu#bci        
by #cb-,me,v helium ions from the       
#fj-;inch cyclotron4                    
----------------------------------------
--------------------------------        
#ig     ,berkelium 7,bk7      #bdc      
#aidi2 ,s4 ,g4 ,thompson1 ,a4 ,ghiorso1 
and ,g4 ,t4 ,seaborg2 ,university of    
,california at ,berkeley2 #ce-,me,v     

helium-ion bombardment of               
,am#bda4                                
----------------------------------------
--------------------------------        
#ih     ,californium 7,cf7    #bde      
#aiej2 ,s4 ,g4 ,thompson1 ,k4 ,street1  
,a4 ,ghiorso1 ,g4 ,t4 ,seaborg2         
,university of ,california at           
,berkeley2 #ce-,me,v helium-ion         
bombardment of ,cm#bdb4                 
----------------------------------------
--------------------------------        
#ii     ,einsteinium 7,es7    #bec      
#aieb-ec2 ,a4 ,ghiorso1 ,s4 ,g4     #ajj
     ,fermium 7,fm7        #bee         
,thompson1 ,g4 ,h4 ,higgins1 ,g4 ,t4    
,seaborg1 ,m4 ,h4 ,studier1 ,p4 ,r4     
,fields1 ,s4 ,m4 ,fried1 ,h4 ,diamond1  
,j4 ,f4 ,mech1 ,g4 ,l4 ,pyle1 ,j4 ,r4   
,huizenga1 ,a4 ,hirsch1 ,w4 ,m4         
,manning1 ,c4 ,i4 ,browne1 ,h4 ,l4      
,smith1 ,r4 ,w4 ,spence2 ,mike          
explosion in ,south ,pacific2 work      
done at ,university of ,california      
at ,berkeley1 ,los ,alamos ,scientific  

,laboratory1 and ,argonne ,national     
,laboratory2 both elements created      
by multiple capture of neutrons in      
uranium of first detonation of a        
thermonuclear device4 ,the elements     
were chemically isolated from the       
debris of the explosion4                
----------------------------------------
--------------------------------        
#aja     ,mendelevium 7,md7    #bef     
#aiee2 ,a4 ,ghiorso1 ,b4 ,g4 ,harvey1   
,g4                                     
,r4 ,choppin1 ,s4 ,g4 ,thompson1 ,g4 ,t4
                                        
,seaborg2 ,university of ,california    
at ,berkeley2 #da-,me,v helium-ion      
bombardment of ,es#bec in #fj-;inch     
cyclotron4                              
----------------------------------------
--------------------------------        
#ajb     ,unnamed,b          #bed       
#aieh2 ,a4 ,ghiorso1 ,t4 ,sikkeland1 ,a4
                                        
,e4 ,larsh1 ,r4 ,m4 ,latimer2           
,university of ,california1 ,lawrence   

,radiation ,laboratory1 ,berkeley2      
#fh-,me,v carbon-ion bombardment of     
,cm#bdf in heavy-ion linear             
accelerator 7,hilac74                   
----------------------------------------
--------------------------------        
#ajc     ,lawrencium          #beg      
#aifa2 ,a4 ,ghiorso1 ,t4 ,sikkeland1 ,a4
                                        
,e4 ,larsh1 ,r4 ,m4 ,latimer2           
,university of ,california1 ,lawrence   
,radiation ,laboratory1 ,berkeley2      
#gj-,me,v boron-ion bombardment of      
,cf#bej1 ,cf#bea1 and ,cf#beb           
in ,hilac4     ,b ,a #aieg claim for the
 synthesis and identification of element
 #ajb was accepted at that time by the  
,international ,union of ,pure and      
,applied ,chemistry1 and the name       
nobelium 7symbol ,no7 was adopted4 ,the 
,university of ,california scientists1  
,a4 ,ghiorso et al41 cited here believe 
they have disproved the earlier claim   
and have the right to suggest a         
different name for the element4