Why does oxygen carry the positive F.C in [CH3OH2]+?

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SUMMARY

The discussion centers on the Lewis structure of the cation [CH3OH2]+, highlighting that the oxygen atom carries a positive formal charge despite its higher electronegativity compared to carbon. The participant notes that the electronegativity difference between carbon and oxygen is 0.9 on the Pauling scale, indicating a polar covalent bond. The confusion arises from the expectation that the most electronegative atom should hold the negative formal charge, leading to a deeper exploration of Lewis structure rules and the role of lone pairs in stabilizing charges.

PREREQUISITES
  • Understanding of Lewis structures and formal charge calculations
  • Familiarity with electronegativity concepts, particularly the Pauling scale
  • Knowledge of polar covalent bonds and their characteristics
  • Basic principles of molecular geometry and lone pair interactions
NEXT STEPS
  • Research the rules for determining formal charges in complex molecules
  • Study the implications of electronegativity differences on molecular bonding
  • Learn about the role of lone pairs in molecular stability and charge distribution
  • Explore advanced Lewis structure examples involving cations and anions
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Chemistry students, educators, and anyone studying molecular structure and bonding, particularly in organic chemistry and cation formation.

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Homework Statement


Find the lewis structure for [CH3OH2]+

Homework Equations


n/a

The Attempt at a Solution


I found the lewis structure to have a positive formal charge on the oxygen. I'm not sure why the oxygen would have the + f.c. since it is much more electronegative than fairly neutral carbon. I initially wanted carbon to have an incomplete octet, so it would carry the + charge, but that did not work.
 
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I just looked up the electronegativity difference (Pauling scale) for Carbon and oxygen=0.9

So... this would be a polar covalent bond.

However, basic lewis structure rules say that the most electronegative atom should carry the negative formal charge. Right?
 
Start with CH3OH, then look for a lone pair which can hold H+.
 

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