Matching Pairs Atoms and APEMANOnline version Parts of the atom and APEMAN matching (8.5A) by James Dycus 1 A 2 3 A (M-A) 4 N 5 6 7 8 E 9 10 11 12 M 13 P Electrons located in the outermost electron shell. This is the shell responsible for chemical reactivity. (Valence Electron) Subatomic particle with a neutral (0) charge and a mass of 1 atomic mass unit (1 amu) (Neutron) Atomic Number Atomic Number (M-A) Number of Neutrons Area located outside of the dense compact core. This area is mostly empty space and is where all the electrons are located. (Electron Cloud) The dense and compact core of the atom that contains all of the protons and neutrons. (Nucleus) Circular areas that make up the electron cloud. These shells are the path that electrons take as they constantly move around the nucleus. (Energy Shells/Electron Shells) Atomic Mass Number of Electrons Subatomic particle with a positive (+1) charge and a mass of 1 atomic mass unit (1 amu) (Proton) Subatomic particle that has a negative (-1) charge and has zero atomic mass units (0 amu) (Electron) Number of Protons