Electronic Structure of the Atom 。An atom has a dense, positively charged nucleus electron density surrounded by a cloud of electrons. The electron density is distance← distance from the nucleus highest at the nucleus and drops off exponentially with nucleus increasing distance from the nucleus in any direction. Chapter 1 5Chapter 1 5 Electronic Structure of the Atom • An atom has a dense, positively charged nucleus surrounded by a cloud of electrons. • The electron density is highest at the nucleus and drops off exponentially with increasing distance from the nucleus in any direction