You are taking the "create" and "destroy" far too literal.
And while you presented a quote about chemical reaction, which is largely correct, the nucleosynthesis is a process unlike any typical chemical reaction.
Now, I am not chemistry expert, but I do recall that a molecule like water, consist of 2 different atoms, oxygen and hydrogen.
Oxygen by themselves, as a element, is a gas with two oxygen atoms (O
2), is itself, a matter.
Likewise, hydrogen by themselves, is an element of gas comprising of two hydrogen atoms (H
2), is itself a different matter to oxygen.
Both gases, are different matters with different structures and different properties.
Water molecule (H
2O) at room temperature, is a new matter, which have different structure and properties to that of hydrogen gas and to that of oxygen gas.
My point is that water molecule is a chemical reaction, where they bonded 3 atoms together, due to these 3 atoms are missing missing 2 electrons. By bonding together the molecule becomes stable, and electrically neutral.
HOWEVER, chemical composition of the water molecule, can still be recognised as 3 atoms (2 hydrogen and 1 oxygen atoms).
Chemical reaction occurred because one atom is missing one or more electrons, which make atom positive-charged, and therefore receptive in bonding with another negative-charged atom or two, to balance out the charged atoms.
But the nucleosynthesis process is very different from chemical reaction of molecule, because in a chemical reaction the number of proton and neutron particles remained the same inside each individual atoms within molecule or compound.
The thing to remember in ordinary chemical reaction, is that it doesn't change the the contents (eg the number of protons and neutrons) inside the nucleus.
For instance, each hydrogen atom within a water molecule will still have only one proton and no neutron, while the oxygen atom will still have 8 protons and 8 neutrons. The nuclei of 3 atoms that make water, are unchanged.
For instance, the mass spectrometry machine can break down material of any compound into smaller molecules or elements.
Nucleosynthesis work very differently, because it is about changing the nuclei of lighter atoms into a single new and heavier nucleus. It is about building a new atom from pre-existing lighter atoms, by joining 2 (or more) nuclei together into a single heavier nucleus, through nuclear fusion.
In a main sequence stars, like our yellow dwarf star - the Sun - the most abundant element in the star is hydrogen, and helium being the 2nd most abundant.
As you know, hydrogen atom only have one proton, but no neutron particles within its nucleus, while helium atom is comprised of 2 protons and 2 neutrons within the helium nucleus (so relative mass of 4).
In a
Stellar Nucleosynthesis, the star's temperature would fuse a bunch of hydrogen (6 of them) together to make the extra proton and 2 neutrons, within a single helium nucleus.
Since hydrogen has no neutron particle, the making of helium nucleus involved 3 steps of fusion of hydrogen atoms.
When 2 hydrogen atoms collided and are fused together into one nucleus, one proton will remain intact, but the 2nd proton will become neutron as so hydrogen will have 2 particles, thereby become hydrogen-2 (or 2H). The collision will cause positron and neutrino to be released.
A second pair of hydrogen atoms would fuse together into another hydrogen-2, in the same way that I've described above.
Another hydrogen atom would collide with each hydrogen-2 atom, causing release of gamma ray, and each hydrogen-2 will inherit extra proton, so that it become helium-3 (2 protons, 1 neutron = 3He).
When the two helium-3 atoms collided and fused, it become a single nucleus of 2 protons and 2 neutrons, hence helium-4; the extra protons will be knocked out as normal hydrogen atoms.
A diagram of hydrogen fusion can be seen in Wikipedia article on Stellar Nucleosynthesis:
The helium atom was produced from hydrogen atoms, during the process of Stellar Nucleosynthesis.
When our Sun run out of hydrogen to fuse at the star's core, it will start to fuse helium atoms, to form heavier elements, like carbon or oxygen atoms.
When that (helium fusion) start, the sun will start to die, and our sun will become hotter, larger in volume and more massive, turning into a red giant star. Outer layers of the sun, will expel debris in every direction until it can no longer fuse, and all that left of the sun is a white core, hence our sun will become a white dwarf.
What you have to remember is that nucleosynthesis involved production of new atomic nuclei from lighter elements, and chemical reaction don't make any new nuclei.
So basically helium as a matter get created from completely different matters, hydrogen.
