Atom Structure DialogueOnline version Explore nucleus, shells, and electrons. by eric mambo Tutor Let's review the structure of an atom. Student An atom has a nucleus and electrons surrounding it. Tutor What's inside the nucleus? Student Protons and neutrons form the nucleus. Tutor And the electrons are held around by what force? Student The electrostatic attraction between negatively charged electrons and the positively charged nucleus. Tutor Tell me about electron shells. Student Electrons occupy shells or orbitals around the nucleus, with increasing energy. Tutor Which particles define the atomic number and mass number? Student The protons define the atomic number, and protons plus neutrons define the mass number.
