a) What does the number on the upper left represent and which subatomic particle can change this number (but not the symbol for the element!!)? Support your answer with a specific example from the simulation (i. e. describe the change you can make that will altex this number).

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.