Author Topic: Herman Anderson  (Read 24168 times)

0 Members and 2 Guests are viewing this topic.

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #8 on: March 26, 2016, 19:50:44 pm »
 
 Chem4kids.com Home LinkChem4kids.com Sections

Neither Here nor There
Different numbers of neutrons in the nucleus can create isotopes Neutrons are the particles in an atom that have a neutral charge. They aren't positive like protons. They aren't negative like electrons. But don't start thinking that they aren't important. Every piece of an atom has huge importance to the way the atom acts and behaves. Neutrons are no exception.

So, if an atom has equal numbers of electrons and protons, the charges cancel each other out and the atom has a neutral charge. You could add a thousand neutrons into the mix and the charge would not change. However, if you add a thousand neutrons, you will be creating one super-radioactive atom. Neutrons play a major role in the mass and radioactive properties of atoms. You may have read the page on isotopes. Isotopes are created when you change the normal number of neutrons in an atom.
Inside the Nucleus
Radioactive decay releases a neutron You know that neutrons are found in the nucleus of an atom. Under normal conditions, protons and neutrons stick together in the nucleus. During radioactive decay, they may be knocked out of there. Neutron numbers are able to change the mass of atoms, because they weigh about as much as a proton and electron together. If there are many atoms of an element that are isotopes, the average atomic mass for that element will change. We have spoken about carbon (C) having an average mass of 12.01. It's not much different than you would expect from an atom with 6 protons and 6 neutrons. The number of carbon isotopes doesn't change the atomic mass very much. As you move higher in the periodic table, you will find elements with many more isotopes.
One Special Element
Did we say that all atoms have neutrons? Oops. All elements have atoms with neutrons except for one. A normal hydrogen (H) atom does not have any neutrons in its tiny nucleus. That tiny little atom (the tiniest of all) has only one electron and one proton. You can take away the electron and make an ion, but you can't take away any neutrons. Hydrogen's special structure becomes very important when you learn how hydrogen interacts with other elements in the periodic table. If you learn about nuclear fusion you will learn about deuterium and tritium. Deuterium is a hydrogen atom with an extra neutron and tritium has two extra. You won't find much deuterium in your backyard. It's mainly in oceans. Don't worry if you do find it, it's not radioactive. It's a stable isotope.

Next Page on Atoms
Return to Top of Page
Or search the sites for a specific topic.

  Search


 

Related Links
Chem4Kids: Isotopes
Biology4Kids: Scientific Method
Geography4Kids: Energy Quanta
Geography4Kids: Magnetic Fields
Cosmos4Kids: Solar Winds
Cosmos4Kids: Sun
Physics4Kids: Modern Physics
Physics4Kids: Nuclear Physics



Superfluid Cores of Stars (Science@NASA Video)
Useful Reference Materials
Encyclopedia.com:
http://www.encyclopedia.com/topic/neutron.aspx
Wikipedia:
http://en.wikipedia.org/wiki/Neutron
Encyclopædia Britannica:
http://www.britannica.com/EBchecked/topic/410919/neutron

Chem4Kids Sections
Matter | Atoms | Elements & Periodic Table | Reactions | Biochemistry
Site Tour | Site Map | Home Page | Glossary | Activities & Quizzes

Rader's Network of Science and Math Sites
Cosmos4Kids | Biology4Kids | Chem4Kids | Geography4Kids | Physics4Kids | NumberNut

Help Page Go for site help or a list of chemistry topics at the site map!
©copyright 1997-2016 Andrew Rader Studios, All rights reserved.
Current Page: Chem4Kids.com | Atoms | Neutrons
** Andrew Rader Studios does not monitor or review the content available at external web sites. They are paid advertisements and neither partners nor recommended web sites. Specific links for books on Amazon.com are only suggested starting points for further research. Please browse, research options, and choose the appropriate materials for your needs.

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #9 on: March 26, 2016, 19:54:56 pm »
Neutron Madness
Isotopes are atoms of elements with different numbers of neutrons We have already learned that ions are atoms that are either missing or have extra electrons. Let's say an atom is missing a neutron or has an extra neutron. That type of atom is called an isotope. An atom is still the same element if it is missing an electron. The same goes for isotopes. They are still the same element. They are just a little different from every other atom of the same element.

For example, there are a lot of carbon (C) atoms in the Universe. The normal ones are carbon-12. Those atoms have 6 neutrons. There are a few straggler atoms that don't have 6. Those odd ones may have 7 or even 8 neutrons. As you learn more about chemistry, you will probably hear about carbon-14. Carbon-14 actually has 8 neutrons (2 extra). C-14 is considered an isotope of the element carbon.
Messing with the Mass
If you have looked at a periodic table, you may have noticed that the atomic mass of an element is rarely an even number. That happens because of the isotopes. If you are an atom with an extra electron, it's no big deal. Electrons don't have much of a mass when compared to a neutron or proton.

Many atoms of the same element have different atomic masses Atomic masses are calculated by figuring out the amounts of each type of atom and isotope there are in the Universe. For carbon, there are a lot of C-12, a couple of C-13, and a few C-14 atoms. When you average out all of the masses, you get a number that is a little bit higher than 12 (the weight of a C-12 atom). The average atomic mass for the element is actually 12.011. Since you never really know which carbon atom you are using in calculations, you should use the average mass of an atom.

Bromine (Br), at atomic number 35, has a greater variety of isotopes. The atomic mass of bromine (Br) is 79.90. There are two main isotopes at 79 and 81, which average out to the 79.90amu value. The 79 has 44 neutrons and the 81 has 46 neutrons. While it won't change the average atomic mass, scientists have made bromine isotopes with masses from 68 to 97. It's all about the number of neutrons. As you move to higher atomic numbers in the periodic table, you will probably find even more isotopes for each element.
Returning to Normal
If we look at the C-14 atom one more time, we find that C-14 does not last forever. There is a time when it loses its extra neutrons and becomes C-12. The loss of those neutrons is called radioactive decay. That decay happens regularly like a clock. For carbon, the decay happens in a few thousand years (5,730 years). Some elements take longer, and others have a decay that happens over a period of minutes. Archeologists are able to use their knowledge of radioactive decay when they need to know the date of an object they dug up. C-14 locked in an object from several thousand years ago will decay at a certain rate. With their knowledge of chemistry, archeologists can measure how many thousands of years old an object is. This process is called carbon dating

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #10 on: March 26, 2016, 20:00:39 pm »
Deuterium is a hydrogen atom with an extra neutron

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #11 on: March 26, 2016, 20:06:34 pm »
When hydrogen loses its electron, the following cations can be formed:

Hydron: general name referring to the positive ion of any hydrogen isotope (H+)
Proton: 1H+ (i.e. the cation of protium)
Deuteron: 2H+, D+
Triton: 3H+, T+
In addition, the ions produced by the reaction of these cations with water as well as their hydrates are called hydrogen ions:

Hydronium ion: H3O+
Zundel cation: H5O2+ (named for Georg Zundel)
Eigen cation: H9O4+ (named for Manfred Eigen)
Zundel cations and Eigen cations play an important role in proton diffusion according to the Grotthuss mechanism.

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #12 on: March 26, 2016, 20:09:47 pm »
Neutron moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235 or a similar fissile nuclide.

Commonly used moderators include regular (light) water (roughly 75% of the world's reactors)

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #13 on: March 26, 2016, 20:13:16 pm »
This suggests that a few decimeters of water is pretty efficient at moderating fast neutrons down to room temperature, but a few meters are required to completely convert thermal neutrons into gamma rays due to capture on hydrogen (energy 2 MeV). A few meters of water is pretty efficient at turning gamma rays into heat.

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #14 on: March 26, 2016, 20:32:13 pm »
Termal neutron capturing during electrolysis.

Potassium hydroxy mol has 20 neutron and 19 electrons and 19 protons.

Online Login to see usernames

  • Administrator
  • Hero member
  • ****
  • Posts: 4443
    • water structure and science
Re: Herman Anderson
« Reply #15 on: March 26, 2016, 20:46:40 pm »
Or...
Neutrons Come from:
Medium neutron sources
Bremssstrahlung from Electron Accelerators / Photofission. Energetic electrons when slowed down rapidly in a heavy target emit intense gamma radiation during the deceleration process. This is known as Bremsstrahlung or braking radiation. The interaction of the gamma radiation with the target produces neutrons via the (γ,n) reaction, or the (γ,fission) reaction when a fissile target is used. e-→Pb → γ→ Pb →(γ,n) and (γ,fission). The Bremsstrahlung γ energy exceeds the binding energy of the “last” neutron in the target. A source strength of 1013 neutrons/second produced in short (i.e. < 5 μs) pulses can be readily realised.
Dense plasme focus. The dense plasma focus (DPF) is a device that is known as an efficient source of neutrons from fusion reactions. Mechanism of dense plasma focus (DPF) is based on nuclear fusion of short-lived plasma of deuterium and/or tritium. This device produces a short-lived plasma by electromagnetic compression and acceleration that is called a pinch. This plasma is during the pinch hot and dense enough to cause nuclear fusion and the emission of neutrons.
Light ion accelerators. Neutrons can be also produced by particle accelerators using targets of deuterium, tritium, lithium, beryllium, and other low-Z materials. In this case the target must be bombarded with accelerated hydrogen (H), deuterium (D), or tritium (T) nuclei.