Nuclear Reactions.

[Warhead]

Hi everyone I am new to here, so here goes my first question!

 

I have a question, how does scientists created elements like Plutonis, since in nuclear reactions are used with atoms with a lower atomic number than the artificial elements and using fission, how can scientists get elements with higher atomic number?

 

 

PS: I am portuguese so all mine education is in portuguese, most of mine scientific vocabulary must be wrong but I think u will understand it

[5614]

Elements like plutonium or uranium can be found isolated or more usually in compounds from which it is extracted (usually enriched) and can then be used in nuclear reactions.

[Warhead]

ok, that its for natural elements, found in earth, but to obtain elements with higher atomic number from a natural element (maybe I am not explaining this right I will give it a try), for example when we do a fission with U-235 in Sr - 90 plus Xe - 143, we get normal elements, how do we get higher mass and atomic elements like artificial like Boris Z = 108 without fusion?

[DV8 2XL]

By nuking them! You can put a sample in a high neutron flux inside a nuclear reactor to produce any number of isotopes commercialy, or the beam from a particle accelerator to make in in small experimental amounts.

[insane_alien]

if you smash two smaller nuclei eg two lead atoms hard enough they stick together.

[jdurg]

Just to make sure we aren't going over your head with the topics here, you are aware of the different ways in which a radioactive atom decays, correct? There's alpha decay in which the atom spits off a helium nucleus and its mass drops by four and its atomic number drops by two. So U-238 (Z=92) spits off an alpha particle and becomes Th-234 (Z=90). Then we also have beta decay where a neutron inside the nucleus breaks apart into a proton and an electron where the electron gets thrown out of the nucleus. In this case, U-239 (Z=92) decays and becomes Np-239 (Z=93) while giving off an electron. There are a few other types of radioactive decay such as spontaneous fission, electron capture, etc. etc. but alpha and beta decay are the two more important ones. (There's also gamma ray emission, but that doesn't result in a new isotope or element being made).

 

Inside nuclear reactors there are great number of nuclear reactions going on. In power plants, the majority of the reactions are the fission of certain isotopes. As you mentioned earlier, these fission events result in the creation of smaller atomic number nuclei. In addition, the fission results in the creation of neutrons. These neutrons do a few things; They either hit a nucleus causing it to split apart and spit out more neutrons, or they are absorbed by a nucleus causing a different reaction to occur, or they bounce around doing nothing.

 

If the neutron is travelling at the right speed it will actually get absorbed by the nucleus of an atom causing that atom's atomic mass to increase by one. Generally speaking, this creates an unstable situation there. As a result, that atom will then decay. If it decays by beta emission, a neutron inside the nucleus will split apart forming a proton and an electron. The atomic number of the atom will go up by one while the mass stays the same. Because of this absorbed neutron, the atom has now increased its atomic number. This happens a LOT inside a nuclear reactor. U-238 will absorb a neutron and form U-239. U-239 isn't all that stable so it decays by spitting out a beta particle thus forming Np-239. Np-239 isn't all that stable either, so it decays and form Pu-239. Relatively speaking, plutonium-239 is somewhat stable so the concentration of plutonium builds up. Because of the absorbed neutrons, the uranium has turned into plutonium. Some isotopes are able to absorb even more neutrons and form higher atomic numbered elements such as Americium, Curium, Berkelium, etc.

 

For the really heavy elements, they take the nuclei of various low mass elements and fling them at high speeds into a target made of a large atomic mass element. Every now and then the two nuclei will merge creating one of these 'superheavy' elements.