The arginine problem asked students to consider the geometry associated with the guanidine group. While the lone pairs were explicitly added to oxygen, I lone pairs were left off the nitrogen atoms on purpose. The goal was to determine whether students correctly used the line structure representation. In the textbook for the course, lone pairs are sometimes provided for heteroatoms, but not always. Two themes were observed with OC1 students. None of the interviewees were successful regarding the activation and productive use of both resources needed: the lone pairs and resonance. One of the two was not activated or productively used in each interview.