The top quark, bottom quark, and charm quark, along with the up quark and down quark, are elementary particles that are considered the building blocks of matter. These quarks are not directly found within the structure of an atom, as they are confined within composite particles called hadrons.
In the context of the atom, the most relevant quarks are the up quark and down quark. The up quark has a charge of +2/3 (in units of elementary charge), while the down quark has a charge of -1/3. These quarks combine to form protons and neutrons, which are the two primary constituents of atomic nuclei.
Protons consist of two up quarks and one down quark, resulting in a net charge of +1. Neutrons, on the other hand, contain two down quarks and one up quark, resulting in a net charge of 0. Protons and neutrons are found within the atomic nucleus, which is located at the center of an atom.
Electrons, which are negatively charged elementary particles, orbit around the atomic nucleus in specific energy levels or electron shells. Electrons are not made up of quarks but are part of a different class of elementary particles known as leptons.
So, while quarks are essential constituents of matter, they are not directly found as isolated particles within atoms. Instead, they combine to form hadrons, such as protons and neutrons, which are the building blocks of atomic nuclei. Electrons, on the other hand, are a different type of elementary particle and are involved in the electron cloud surrounding the atomic nucleus.