Ilt: Forskelle mellem versioner
Content deleted Content added
→Senere historie: Fjerner 2 kilder vedr. Goddard: En nævnte ikke Goddard, en havde dårlig link. Tilføjer ny kilde til erstatning. |
Steenth (diskussion | bidrag) m fix note |
||
Linje 117:
At [[standard temperature and pressure]], oxygen is a colorless, odorless, and tasteless gas with the [[molecular formula]] {{chem|O|2}}.<ref>{{cite web|url=http://www.sciencekids.co.nz/sciencefacts/chemistry/oxygen.html|title=Oxygen Facts|publisher=Science Kids|date=February 6, 2015|accessdate=November 14, 2015}}</ref>
In this ''dioxygen'', the two oxygen atoms are [[chemical bond|chemically bonded]] to each other. The bond can be variously described based on level of theory, but is reasonably and simply described as a covalent [[double bond]] that results from the filling of [[molecular orbitals]] formed from the [[atomic orbital]]s of the individual oxygen atoms, the filling of which results in a [[bond order]] of two. More specifically, the double bond is the result of sequential, low-to-high energy, or [[Aufbau principle|Aufbau]], filling of orbitals, and the resulting cancellation of contributions from the 2s electrons, after sequential filling of the low σ and σ<sup>*</sup> orbitals; σ overlap of the two atomic 2p orbitals that lie along the O-O molecular axis and {{pi}} overlap of two pairs of atomic 2p orbitals perpendicular to the O-O molecular axis, and then cancellation of contributions from the remaining two of the six 2p electrons after their partial filling of the lowest {{pi}} and {{pi}}<sup>*</sup> orbitals.<ref name=Barrett2002>Jack Barrett, 2002, "Atomic Structure and Periodicity, (Basic concepts in chemistry, Vol. 9 of Tutorial chemistry texts), Cambridge, U.K.:Royal Society of Chemistry, p. 153, ISBN 0854046577, see [https://books.google.com/books?isbn=0854046577 Google Books] accessed January 31, 2015.</ref>
This combination of cancellations and σ and {{pi}} overlaps results in dioxygen's double bond character and reactivity, and a triplet electronic [[ground state]]. An [[electron configuration]] with two unpaired electrons, as is found in dioxygen (see the filled {{pi}}* orbitals in the diagram) orbitals that are of equal energy—i.e., [[degenerate orbitals|degenerate]]—is a configuration termed a [[spin triplet]] state. Hence, the ground state of the {{chem|O|2}} molecule is referred to as [[triplet oxygen]].<ref name="BiochemOnline">{{cite web|work=Biochemistry Online|url=http://employees.csbsju.edu/hjakubowski/classes/ch331/oxphos/oldioxygenchem.html |title=Chapter 8: Oxidation-Phosphorylation, the Chemistry of Di-Oxygen|first=Henry|last=Jakubowski|accessdate=January 28, 2008|publisher=Saint John's University}}</ref><ref group=lower-alpha>An orbital is a concept from [[quantum mechanics]] that models an electron as a [[Wave–particle duality|wave-like particle]] that has a spatial distribution about an atom or molecule.</ref> The highest energy, partially filled orbitals are [[antibonding]], and so their filling weakens the bond order from three to two. Because of its unpaired electrons, triplet oxygen reacts only slowly with most organic molecules, which have paired electron spins; this prevents spontaneous combustion.<ref name="Weiss2008" />
| |||