This paper presents a joint experimental and theoretical study of molecular adsorbates on graphene, focusing on the effects of chemical doping. The research reveals a fundamental relationship between the magnetic properties of adsorbates and their doping strength. Paramagnetic molecules, such as the single NO₂ molecule, act as strong acceptors, while their diamagnetic dimer, N₂O₄, causes only weak doping. This difference is attributed to the unique density of states (DOS) of graphene, which provides an ideal platform for studying doping effects in semiconductors. The study also explains the "chemical sensor" properties of graphene, particularly its ability to detect single NO₂ molecules. The electronic structure of graphene is highly sensitive to the presence of impurities, and the type and concentration of charge carriers are crucial for its electronic behavior. Graphene's ability to maintain high mobility even after doping makes it a promising material for future electronics and gas sensing applications. The research identifies two main classes of dopants in graphene: paramagnetic and nonmagnetic. Paramagnetic impurities, due to their magnetic moments, cause strong doping, while nonmagnetic impurities act as weak dopants. This distinction is crucial for understanding the electronic properties of graphene and its potential applications. The study also explores the effects of adsorbates such as NO₂ and N₂O₄ on the electronic structure of graphene. Theoretical calculations using density functional theory (DFT) show that the DOS of graphene is significantly affected by these adsorbates. The results indicate that NO₂ acts as a strong acceptor, while N₂O₄ has a weaker effect. These findings are supported by experimental measurements of the Hall resistance, which confirm the presence of two distinct acceptor levels in graphene. The research highlights the importance of magnetic moments in achieving strong doping effects in graphene. The study also discusses the potential of graphene for future electronic and magnetic applications, emphasizing its unique properties and the importance of understanding the mechanisms behind chemical doping. The findings provide a foundation for further research into the electronic and magnetic properties of graphene-based materials.This paper presents a joint experimental and theoretical study of molecular adsorbates on graphene, focusing on the effects of chemical doping. The research reveals a fundamental relationship between the magnetic properties of adsorbates and their doping strength. Paramagnetic molecules, such as the single NO₂ molecule, act as strong acceptors, while their diamagnetic dimer, N₂O₄, causes only weak doping. This difference is attributed to the unique density of states (DOS) of graphene, which provides an ideal platform for studying doping effects in semiconductors. The study also explains the "chemical sensor" properties of graphene, particularly its ability to detect single NO₂ molecules. The electronic structure of graphene is highly sensitive to the presence of impurities, and the type and concentration of charge carriers are crucial for its electronic behavior. Graphene's ability to maintain high mobility even after doping makes it a promising material for future electronics and gas sensing applications. The research identifies two main classes of dopants in graphene: paramagnetic and nonmagnetic. Paramagnetic impurities, due to their magnetic moments, cause strong doping, while nonmagnetic impurities act as weak dopants. This distinction is crucial for understanding the electronic properties of graphene and its potential applications. The study also explores the effects of adsorbates such as NO₂ and N₂O₄ on the electronic structure of graphene. Theoretical calculations using density functional theory (DFT) show that the DOS of graphene is significantly affected by these adsorbates. The results indicate that NO₂ acts as a strong acceptor, while N₂O₄ has a weaker effect. These findings are supported by experimental measurements of the Hall resistance, which confirm the presence of two distinct acceptor levels in graphene. The research highlights the importance of magnetic moments in achieving strong doping effects in graphene. The study also discusses the potential of graphene for future electronic and magnetic applications, emphasizing its unique properties and the importance of understanding the mechanisms behind chemical doping. The findings provide a foundation for further research into the electronic and magnetic properties of graphene-based materials.