This is an excellent molecular model set for students to understand the basics of molecular structures. Colored plastic balls represent atoms, while 3 different lengths of springs represent different types of molecular bonds. Comes with instructions, springs, and 35 colored plastic balls ( 6 black (carbon), 2 blue (nitrogen), 15 yellow (hydrogen), 4 red (oxygen), 4 green (chlorine), 2 orange (sodium), and 2 purple (potassium).