The nucleus of an atom has a positive charge, specifically a positive integer charge known as the atomic number, which is equal to the number of protons it contains. Protons are positively charged particles.
Nuclei are relatively small and dense compared to the overall size of an atom. They contain nearly all of an atom's mass, but occupy a tiny fraction of the atom's volume. This means that nuclei do not cover a lot of space within the atom. The majority of an atom's volume is occupied by the electron cloud, where electrons are found.