Possible Answers: Sharing electrons between atoms. Electrical conduction. Electron sea. Correct answer: Sharing electrons between atoms. Explanation : To achieve an octet of valence electrons, atoms can share electrons so that all atoms participating in the bond will have full valence shells.
Report an Error. Possible Answers:. Correct answer:. Explanation : The key to this problem is that electrons in covalent bonds are shared and therefore "belong" to both of the bonded atoms. Possible Answers: Spin pairing of electrons. Electron pair shared between two neighboring atoms. Constructive interference between atomic orbitals. Correct answer: All of these. Explanation : A chemical bond is considered covalent if there is sharing of one or more pairs of electrons between atoms.
Copyright Notice. View Physical Chemistry Tutors. Crucially, the compound can be reversibly reduced, cleaving both the S—S and S—O bonds to produce the sulfide again. The ease of this transformation suggests that S IV —S II bond formation and dissociation redox processes could be found in biological systems. Kano, N. Structure and properties of a sulfur IV —sulfur II -bond compound: reversible conversion of a sulfur-substituted organosulfurane into a thiol.
Download references. You can also search for this author in PubMed Google Scholar. Reprints and Permissions. Withers, N. Sulfur, so good. Other atoms can't possibly donate electrons to sulfur and phosphorus in this way. And yet, many chemists including some experts in sulfur and phosphorus chemistry still draw sulfate with double bonds.
Why would they make such a mistake in the face of reason? Partly, it has to do with experimental evidence. Remember, "experimental" sounds wishy-washy and tentative to non-scientists, but to a chemist the term really means "reality-based". One of the reasons people draw double bonds in many sulfur and phosphorus compounds is that the bonds simply behave like double bonds.
That is, they are stronger and shorter than single bonds. We might not think about those bonds in exactly the way we think about double bonds in other situations, but the experimental evidence says that there is some additional attraction between the sulfur and oxygen atoms in these cases.
There is additional evidence that sulfur and phosphorus can "exceed the octet" or form "Lewis-disobedient" structures. Compounds like phosphorus pentafluoride PF 5 clearly require more than four bonds to phosphorus.
Without five bonds, we would need to draw one of the fluorides as an anion. It's certainly possible that this could be the true structure, but there is evidence from X-ray crystallography that all of the fluorines are attached to phosphorus in PF 5 , as well as in the related PF 6 - anion hexafluorophosphate, a very common molecular ion in X-ray crystallographic studies. But those examples can also be drawn in other ways. Are all five of the fluorines in PF 5 really covalently bound, or are some of them ionic?
We could draw this structure in different ways, too. The driving force for excitation is the unpairing of electrons will allow the element to form more covalent bonds, hence more energy is released from the formation of more bonds, and the final configuration will be more stable.
So why wouldn't Period 2 elements such as oxygen undergo excitation? This is because the next available orbital for unpairing of electrons is in 3s subshell, which is in the next principal quantum shell. The energy difference is too big and it requires too much effort for oxygen to unpair its electron and promote it to the 3s subshell. Hence oxygen and other Period 2 elements do not use orbitals in the third principal quantum shell for bonding and cannot expand octet. For the detailed step-by-step discussion on how Period 3 elements expand octet, check out this video!
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