Tag Info

New answers tagged

3

Be-7 is common atmospheric radionuclide produced by cosmic ray spallation of nitrogen and oxygen. Ground level concentration of Be-7 is in order of ~mBq per cubic meter of air. Main deposition process of Be-7 is a wet scavenging which yields to ~Bq per litre of rainwater. It is therefore possible to find Be-7 in background (depends on location of ...


3

The answer is already on page 2 of your link above: "Among the large number of radionuclides of medical interest, Sc-44 is promising for PET imaging. Either the ground-state Sc-44g or the metastable-state Sc-44m can be used for such applications, depending on the moleculeused as vector." So the metastable state Sc-44m decays to the ground state Sc-44g.


0

In "ordinary" water, about 156 out of 1,000,000 hydrogen atoms are deuterium. If you were to pick any instant in time, these atoms would be arranged in water molecules as follows:$$HHO---0.999688024$$ $$HDO---0.000311951$$ $$DDO---0.000000024$$ So only about 24 molecules of true heavy water exist in a billion molecules of ordinary water. In addition, these ...


1

Apart from $D_2O$ (heavy water), natural water also contains $HDO$ (semi-heavy water) and of course $H_2O$. The physical properties of these substances do vary from one to another, as can be seen from this Wikipedia comparative table. For example, the melting point of $D_2O$ differs sufficiently from that of $HHO$ or $H_2O$ to be measurable by a hobbyist or ...


0

Within the Born-Oppenheimer Approximation the different species have the same structure as all nuclei are considered to be infinitely heavy. In fact, you can determine the structure of simple molecules by changing one of the atoms with one of its isotopes (a so-called isotopologue of your initial molecule) and comparing the rotational spectra. Of course the ...


1

The range of attraction between two protons is short. So if you have a large number of protons only the long range repulsive Coulomb force will dominate and the nucleus will not be stable. So you need neutrons which are free from this repulsive force.


11

I'm sure this has been answered elsewhere on the site, so I won't provide too much detail. The nucleus is held together by the strong nuclear force between nucleons (protons and neutrons). The force is short range and effectively only acts between adjacent nucleons. At the same time, the Coulomb repulsion between protons acts over a long range - so that all ...



Top 50 recent answers are included