Ms. Mendeleiev is a strict, sharp-tongued and grouchy teacher who expects her students to be hardworking, focused, and well-behaved, and she becomes cross with her students who are not. She is easily irritated by people bossing her around, but she shows some fear if she finds herself in serious trouble, like with Rogercop in the episode of the same name. She can also be incredibly stubborn and rude, as shown in "Robostus", in which she refuses to believe both Max Kanté and Markov when they claim the latter has real, human emotions. Despite this, she can be tricked somewhat easily, finding herself dumbfounded after Marinette Dupain-Cheng manipulates her into letting her see Mr. Damocles in "Robostus".
- Her surname resembles Dmitri Mendeleev, a Russian chemist who was the founder and compiler of the modern periodic table of elements.
- Despite having her own classroom, in "Antibug", she teaches Miss Bustier's class in Miss Bustier's classroom.
- She also has her own class, but she teaches Caline's class in her own classroom for particular subjects in some episodes like "The Evillustrator" and "Princess Fragrance".
- Ms. Mendeleiev's known students are Aurore Beauréal, Mireille Caquet, and Jean Duparc.