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The common allotrope of elemental oxygen on Earth is called dioxygen, O 2, the major part of the Earth's atmospheric oxygen (see Occurrence). O 2 has a bond length of 121 pm and a bond energy of 498 kJ/mol. [42] O 2 is used by complex forms of life, such as animals, in cellular respiration. Other aspects of O 2 are covered in the remainder of ...
It is formally derived from oxygen by the removal of an electron: O 2 → O + 2 + e −. The energy change for this process is called the ionization energy of the oxygen molecule. Relative to most molecules, this ionization energy is very high at 1175 kJ/mol. [1] As a result, the scope of the chemistry of O +
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.
In chemistry, bond energy (BE) is one measure of the strength of a chemical bond. It is sometimes called the mean bond, bond enthalpy, average bond enthalpy, or bond strength. [1] [2] [3] IUPAC defines bond energy as the average value of the gas-phase bond-dissociation energy (usually at a temperature of 298.15 K) for all bonds of the same type ...
The term bond-dissociation energy is similar to the related notion of bond-dissociation enthalpy (or bond enthalpy), which is sometimes used interchangeably.However, some authors make the distinction that the bond-dissociation energy (D 0) refers to the enthalpy change at 0 K, while the term bond-dissociation enthalpy is used for the enthalpy change at 298 K (unambiguously denoted DH° 298).
Under a molecular orbital theory framework, the oxygen-oxygen bond in triplet dioxygen is better described as one full σ bond plus two π half-bonds, each half-bond accounted for by two-center three-electron (2c-3e) bonding, to give a net bond order of two (1+2× 1 / 2 ), while also accounting for the spin state (S = 1).
Tetraoxygen was first predicted in 1924 by Gilbert N. Lewis, who proposed it as an explanation for the failure of liquid oxygen to obey Curie's law. [1] Though not entirely inaccurate, computer simulations indicate that although there are no stable O 4 molecules in liquid oxygen, O 2 molecules do tend to associate in pairs with antiparallel spins, forming transient O 4 units. [2]
The energy difference of 94.3 kJ/mol between ground state and singlet oxygen corresponds to a forbidden singlet-triplet transition in the near-infrared at ~1270 nm. [12] As a consequence, singlet oxygen in the gas phase is relatively long lived (54-86 milliseconds), [ 13 ] although interaction with solvents reduces the lifetime to microseconds ...