How Atoms Form Molecules:Chemical Bonds 。 The number of protons and electrons is equal in an atom. lons are atoms that have gained or lost electrons and are charged. 00 Loss of 00 Gain of 0 0 electron electron 00 00 00 00 Sodium atom Sodium ion Chlorine atom Chloride ion (electron donor) (Na) (electron acceptor) (C) a Figure 2.2a• The number of protons and electrons is equal in an atom. • Ions are atoms that have gained or lost electrons and are charged. How Atoms Form Molecules: Chemical Bonds Figure 2.2a