Spectroscopy PLEASE HELP

Drag each label to the correct location on the chart. classify each reaction as endothermic or exothermic.

Which of these conditions most likely produces an unstable isotope?

Select all of the statements which are true. electrons are located in shells or orbits around the atom. electrons orbit slowly around the atom. electrons travel in one flat path around the nucleus of an atom. the valence of an atom is determined by the number of electrons in the atom's outermost shell.