Brainlies ! : ) 1. which of the following elements has the highest atomic mass? helium: 2 protons and 2 neutrons nitrogen: 7 protons and 7 neutrons oxygen: 8 protons and 8 neutrons hydrogen: 1 proton and no neutrons 2. which of the following statements does not describe the structure of an atom? an atom has a small, dense center called the nucleus. inside the nucleus of an atom are protons and electrons. protons are positively charged sub-atomic particles. electrons are negatively charged sub-atomic particles.