In the ground state of an atom or molecule, the unpaired electrons usually all have parallel spin. In this case parcha multiplicity is also equal to the number of unpaired electrons plus one. For example, the ground state of carbon atom is a 3P state. Most stable organic molecules have complete electron shells with no unpaired electrons and therefore have singlet ground states.
This is true also for inorganic molecules containing only main-group elements. However, higher spin ground states are very common in coordination complexes of transition metals. A simple explanation of the spin states of such complexes is provided by crystal field theory. In the ground state of dioxygen, this energy level is occupied by two electrons of the same spin, as shown in the molecular orbital diagram. The molecule, therefore, has two unpaired electrons and is in a triplet state. In contrast, the first and second excited states of dioxygen are both states of singlet oxygen.
1 despite the two unpaired electrons. Molecular orbital diagram of two singlet excited states and triplet ground state of O2. In organic chemistry, carbenes are molecules which have carbon atoms with only have six valence electrons and therefore disobey the octet rule. This chemistry-related article is a stub. You can help Wikipedia by expanding it. This article is about women’s one-piece swimwear. A one-piece swimsuit most commonly refers to swimwear worn primarily by women and girls when swimming in the sea or in a swimming pool, playing water polo, or for any activity in the sun, such as sun bathing.