We have already covered how a nucleus can grow through the rules of spherical dense packing.
This was accomplished by adding proton electrons pairs to a nucleus and then
correcting for the number of electrons in the nucleus via beta decay. The simple
nuclear reactions we covered previously are used throughout the process of building larger atoms.
Let's examine how we construct the larger atoms using the Structured Atom Model.
We have so far examined elements up to carbon. Let's explore how this shape changes as we move
up to Calcium. Here you will notice that some structural patterns are starting to emerge.
These are recurring sub structures on top of the carbon like structures. In some sense these are
the building blocks. Let's examine how these fit together and shape the structure of the nucleus.
Nucleus of deuterium: Two protons joined by an inner electron. A deuteron
V-Shaped structure: Two deuterons in a V- shape structure; comparable to a squashed tetrahedron
Nucleus of lithium: A ring of five protons with a cap proton on one side
of the ring packed into three deuterons; the upper part of pentagonal bi-pyramid
Nucleus of beryllium: Four deuterons packed together
Nucleus of boron: Five deuterons packed together
Nucleus of Carbon: Two rings of five protons with a cap proton on top of the upper one
and on the bottom of the lower one; or six deuterons packed together in two rings with caps.
If you have had a chance to look at the SAM nuclei on ethereal matters then you may be interested to
know that the colours you sometimes see relate exactly to these shapes or building blocks
Individual Proton Electron pairs or neutrons
are marked in yellow and a single proton is marked in brown
Lets run through each and explain why they are significant
Two capping. This happens when the icosahedron is growing and just one deuteron is attached to
the carbon like structure. This is called a two ending and is coloured in green
Neutral capping. This occurs when a branch has grown to a neutral point
and is no longer chemically reactive, this means the ending will no longer interact with other
atoms. Four additional protons and two inner electrons have been added
to one side of a carbon like structure in a V-shape. This is called a four ending.
Neutral capping with an additional proton electron pair. An additional proton electron pair is added
to balance the structure or create an isotope - this is called a five ending
Lithium nuclet. The next step in growth following neutral capping
and the additional of a proton electron pair is to add another proton and create a lithium nuclet
Beryllium ending. This is an intermediate state between the lithium and carbon nuclet
Boron ending. This is also an intermediary state
Carbon nuclet. This is a complete icosahedron
Initial ending. Both sides of the carbon are capped with four endings making this
branch completely chemically inert - when all branches are capped the element is noble
Final ending. The final shape of the carbon nuclet represents the effective back bone of the nucleus,
this may also be called a backbone nuclet.
There is a difference between the initial carbon and the following carbons that connect to it.
The connection happens through a shared proton, which means that subsequent carbons in the
backbone provide only 11 protons to the structure, not 12. As a consequence a new secondary carbon
in the backbone only contains 5 deuterons and a single proton, not 6 deuterons.
How this will explain the proton/neutron ratio - as it is going in the opposite direction - is
a topic of a later video.
This does however have an implication for the ratio of protons to neutrons in the nucleus
as the atom grows larger. This is fixed by the quasi inner electrons,
this is a topic we will cover in more detail in a future video.
Phases
Building up to the icosahedron shape (carbon) from the tetrahedron (helium) is
called the building phase. Continuing from the icosahedron to a point where
the nuclets are made inert is defined as the capping phase.
The nucleus grows from element to element as a general rule with steps of two protons
switching between building and capping phases.
Let just recap some definitions
An Ending - this is a stable geometrically arranged cluster of protons and inner electrons
A Nuclet - is a densely packed, geometrically arranged cluster of protons
and inner electrons that belongs to the building phase
Capping - is a geometrically arranged cluster of protons and inner electrons that belong to the
capping phase. These nuclets and capping phases are representative of chemical properties. They
carry these properties with them to larger nuclei, I.e. A lithium nuclet has an oxidation state of 1
and this is carried to the larger nucleus as well. So these first nuclets and capping
phases (first cycle of 8 from Na to Ne) are repeated in all the larger elements!
Branching and elongation
As the elements get larger this scheme means that there are more possibilities in terms of
where the nucleus can grow. This is one of the main reasons there are many transition metals.
In general during the growth the building phase seems to be preferred
over the capping phase. This probably has a lot to do with the increasing options available
and therefore the chance of a nuclet completing before another spot starts growth is reduced.
This means we see growth at several places on the nucleus in parallel.
To get a better understanding of what is happening we must look at the basic nuclet structure.
As we grow the nucleus we can see that the perfect carbon shape becomes distorted.
With sulfur, chlorine and argon we reach the state of two distorted carbon nuclets.
This likely means that energetically the nucleus would like to be in a completely noble state,
and that the lithium nuclets are not the preferred configuration. Yet they are the
only option when the elements grow and if they area is available for proton capture
(5-ending) and neutron capture (4-ending) then a Lithium ending will still be created.
Potassium is the next alkali metal, this has a lithium nuclet on one end. Moving on to calcium
we see there are now two lithium nuclets and this creates the first branch in the structure.
Moving along we see copper which has four carbon nuclets, but they are not completely capped
If we now jump to Krypton, this is inert as it is completely capped with 5 carbon nuclets.
The branching continues, the nucleus elongates in the process of adding new carbon nuclets to
the backbone structure. If the structure did not elongate but we added to the first branch
we would see colliding branches very early on,
and would therefore be unable to create heavier elements that we know do exist in nature.
If we now look at the structure of silver and compare it to the structure of xenon,
it should be clear to see why silver is considered a noble metal.
Gold too show this same property
Colliding branches
Collisions, or close contact of branches happens
just after lead, which also happens to be one of the last stable elements!
Radon is the next noble element, but is unstable and decays
If we examine Uranium we can see more clearly the problem with two branches coming
too close to each other. Further growth on that spot would lead to overlapping of potential spots,
hence it must and will react. If the structure allows it, an alpha
particle or larger chunks are ejected. Uranium therefore decays to other daughter products.
The proximity of the branches is what causes the natural radioactivity in most of the
elements. This is a topic we will discuss in more detail with the SAM team in a separate video.
Elements above lead are unstable because the nucleus can no longer provide a stable
configuration. There is always a balance with the nucleus wanting to be in the densest packing state
but there are limited points from which the structure can grow. This leads to the fact that
individual branches are in the densest packing configuration but the nucleus as a whole is not.
The reason there are still elements above lead is due to the fact that the nucleus is more or
less overloaded in a semi stable state. It can do this because the outer ending can structurally
still hold the next viable configuration. The nucleus becomes elongated, because if it did not
it would decay much sooner… but there is a limit The last unstable but structurally sound element
which can be created with SAM is americium. Elements above americium are artificial
and can only be created by fusing nuclei together with brute force.
The resulting nucleus is without structure that can be described with SAM
and only exists for a few milliseconds before fissioning again.
The building of the nucleus using these rules through the alternation between building and
capping is what leads to the periodicity or cycle of 8 we see in the Periodic Table.