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Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium. [68] About 0.9% of the Sun's mass is oxygen. [19] Oxygen constitutes 49.2% of the Earth's crust by mass [69] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust.
In molecular physics, the molecular term symbol is a shorthand expression of the group representation and angular momenta that characterize the state of a molecule, i.e. its electronic quantum state which is an eigenstate of the electronic molecular Hamiltonian. It is the equivalent of the term symbol for the atomic case.
For molecular term symbols, Greek letters are used to designate the component of orbital angular momenta along the molecular axis. The use of the word term for an atom's electronic state is based on the Rydberg–Ritz combination principle , an empirical observation that the wavenumbers of spectral lines can be expressed as the difference of ...
This state is referred to by the title term, singlet oxygen, commonly abbreviated 1 O 2, to distinguish it from the triplet ground state molecule, 3 O 2. [2] [3] Molecular orbital theory predicts the electronic ground state denoted by the molecular term symbol 3 Σ – g, and two low-lying excited singlet states with term symbols 1 Δ g and 1 ...
Atomic oxygen, denoted O or O 1, is very reactive, as the individual atoms of oxygen tend to quickly bond with nearby molecules. Its lowest-energy electronic state is a spin triplet, designated by the term symbol 3 P. On Earth's surface, it exists naturally for a very short time.
The molecular term symbol is a shorthand expression of the angular momenta that characterize the electronic quantum states of a diatomic molecule, which are also eigenstates of the electronic molecular Hamiltonian. It is also convenient, and common, to represent a diatomic molecule as two-point masses connected by a massless spring.
The resulting electron configuration can be described in terms of bond type, parity and occupancy for example dihydrogen 1σ g 2. Alternatively it can be written as a molecular term symbol e.g. 1 Σ g + for dihydrogen. Sometimes, the letter n is used to designate a non-bonding orbital. For a stable bond, the bond order defined as
This notation is used to specify electron configurations and to create the term symbol for the electron states in a multi-electron atom. When writing a term symbol, the above scheme for a single electron's orbital quantum number is applied to the total orbital angular momentum associated to an electron state. [4]