The presence of electrons orbiting around the nucleus of an atom and the absence of negative charges in the nucleus can be explained by the understanding of atomic structure and the fundamental particles that make up an atom.
An atom consists of three main subatomic particles: protons, neutrons, and electrons. Protons have a positive charge, neutrons have no charge (they are neutral), and electrons have a negative charge. The protons and neutrons reside in the nucleus at the center of the atom, while the electrons occupy regions around the nucleus called electron orbitals or electron shells.
The reason there are no negative charges (electrons) in the nucleus is due to the differing forces that govern these particles. The nucleus is composed of protons and neutrons, which are held together by strong nuclear forces. These forces are short-range and act to bind the protons and neutrons in the nucleus. The strong nuclear forces are much stronger than the electrostatic repulsion between the positively charged protons.
On the other hand, electrons are negatively charged and are attracted to the positively charged protons in the nucleus via the electromagnetic force. Electromagnetic forces act over longer distances and are responsible for the attraction between the electrons and protons.
The electron's behavior within an atom is best described by quantum mechanics, where electrons exist in probability distributions or orbitals around the nucleus rather than in well-defined orbits. These orbitals represent regions of space where the probability of finding an electron is highest.
In summary, the absence of negative charges (electrons) in the nucleus can be attributed to the different types of forces acting on protons and electrons. The strong nuclear forces hold the positively charged protons together in the nucleus, while the electromagnetic forces attract the negatively charged electrons to the nucleus, resulting in the electron orbitals or shells around the nucleus.