This sounds very much like a chicken-egg problem.
The first thing that formed must be hydrogen nuclei. The only other alternative is that the atom was created instantly, and the nuclei sprang forth at the same time as the atom, meaning that neither was technically first. The logic is that an atom can’t form without a nucleus, but it theoretically could be created instantly.
I’d say market and distribution would be the next step
Atoms with the same number of protons, but different numbers of neutrons are isotopes of the same element.
Electronnegativity increase because the number of charges on the nucleus increases. Which attracts the bonding amount of electrons more.
1500 cm^3 ; 1 mL equals 1 cm^3
