What parts make up the nucleus?
Protons and neutrons
The standard, simple model of an atom is just a bunch of packed balls, called neutrons and protons, tightly packed together due to the strong force in a region called the nucleus. Outside the empty space, electrons orbit the atom in electron clouds, which are regions where electrons are likely to be found, called orbitals.
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The nucleus is made up of protons, the positively-charged particles, and neutrons, the neutrally-charged particles, which have a net zero charge.