INSIDE THE NUCLEUS

INSIDE THE NUCLEUS

ATOMS AND MATTER| ASTROPHYSICS CHEMISTRY

Let's start by talking about how the atomic nucleus is constructed.

Let’s look at the table which you see down below.

This table lists several chemical elements from the very beginning of the periodic table of chemical elements with numbers 1, 2, 3, 4, 5 and so on. And here in this table are not listed only the numbers of elements but also their so-called masses (or mass numbers).

Some integer figures are approximately proportional to the mass of this or that atom.

And we may see that those mass numbers for very many elements are all approximately twice as big as their number of orders in that table.

 For example, let’s take helium: number – 2, mass number – 4. Let’s take oxygen: number – 8, mass number –16.Nitrogen: number – 7, mass number – 14. And for many elements it is approximately the same. If you go, I would say, further through the table of chemical elements, than you may notice, that this ratio too a little bit changes, but not strongly.

For heavier atomic elements this ratio is a little bit greater than two. It may be two and a half. You see it on the graph, which is also now you can see. But still the fact that for very many elements this ratio is exactly equal to two, brings us to certain conclusions. 

And one of these possible conclusions is that, probably the nucleus is not an integer object, it is also a compound, it is also something that consists of parts. We know, that the atomic nucleus has a positive electric charge exactly equal to the charge of all the electrons circling this or that atom. 

Probably among the parts, which you may find inside the nucleus there should be some small parts which carry positive electric charge exactly equal to the charge of the electron, but positive. And then, if for example you take the atom of oxygen with 8 electrons, you should have 8 these new positively charged particles inside the nucleus.

 Those positively charged hypothetical particles we now call “protons”. And we may find protons simply as a nucleus of the hydrogen atom. The hydrogen atom is the simplest one. And one proton serves as a nucleus for this atom usually then the question arises: “How do those protons manage to live together?”

 They all are positively charged. And it means that they must repulse from each other, and repulse very strongly. It means that there should be some other force that keeps them together. Not electrostatic! Not electromagnetic!

And the fact, that the mass number of many nuclei doubles the number of these atoms in the periodic table, also additionally means that not only protons do exist inside the nucleus, but also some other particles, which have approximately the same mass as the proton and which also do exist inside the nucleus approximately in the same quantity as protons. 

For example, the nucleus of helium should have two protons (the charge should be equal to the charge of two electrons) plus additionally two other particles having approximately the same mass as protons, but no electric charge. 

Those particles are called now “neutrons”. Heavier elements of matter have the number of protons equal to the number of electrons and the number of neutrons which can a little bit exceed the number of protons. We know this again from the periodic table of chemical elements as their mass numbers exceed the ratio of the mass number to the number of the element in the table exceeds value two.

 There some experimental evidence in favour of this idea – alpha particles, alpha particles which consist of two protons and two neutrons, alpha particles that are known since the end of the 19th century as certain emanations from uranium or radium and which were used by Rutherford for his experiments, with a help of which we now know how atoms… we know about the existence of the atomic nucleus.

But neither protons or neutrons initially were discovered in the experiments.

They were discovered later. So we may suppose that the atomic nucleus consists of the particles of two types: positively charged protons (and their number exactly equals to the number of electrons circling around the nucleus) and electrically neutral neutrons.

And the number of neutrons either equals to the number of protons or is exceeding it for heavier elements. Exceeding, but not strongly.

In order to keep all this together there should exist some new unknown up to now interaction: not electrostatic, not electromagnetic something new, that keeps all these things together. Because, if only electromagnetic interaction and gravitation do exist in this world, then no nucleus could be stable.

 Because positively charged protons would strongly repulse from each other and neutrons, as they are electrically neutral, should simply be also spread all over the space together with protons. There should be some other force, that is keeping all of them together. This new force should be very strong. And we call it “strong interaction” now. 

Strong interaction is the third force which is necessary to explain why the matter exists in the form in which it exists.