Lewis Structure of CH3+, the Methenium Ion (with VSEPR Shape and Hybridization)

CH3+ is what you get when you rip an H- ion away from methane. This is not an easy task; lots of energy is needed. It can happen inside a mass spectrometer though.

This ion has one carbon atom (which brings four valence electrons with it) and three hydrogens (each of which bring one valence electron with it). This makes seven valence electrons total, however you must “remove” one because of the positive charge on the ion. This means you are left with just six valence electrons to work with.

Six electrons is just enough for three bonding pairs; this holds each of the hydrogen atoms to the carbon atom via sigma (single) bonds, and nothing else. There is no lone pair on any of the atoms here.

VSEPR Shape of CH3+ and Hybridization of Carbon in CH3+

This carbon atom needs to make three single (sigma) bonds; this implies it will have sp2 hybridization and trigonal planar geometry. The leftover, unhybridized, 2p orbital from carbon sits empty, perpendicular to the plane of the molecule. Its openness and readiness to accept a lone pair from any other particle is what makes this particle very react.


Lewis Structure of MgS (Magnesium Sulfide), an Ionic Compound

Magnesium is a metal that brings two valence electrons in its outer shell. It wants to lose these two electrons so that its “outer shell” is empty.

Sulfur is a non-metal that brings six valence electrons with it; it wants to gain exactly two electrons to complete its outer shell.

This makes Magensium and Sulfur a great match for each other; magnesium gives its two valence electrons to sulfur, and that’s it.

You must show square brackets around each ion, along with its charge, to emphasize that you are not creating a molecule. You are creating an ionic lattice of alternating positive and negative charges.


Lewis Structure of C2H6 (Ethane) Step-by-Step

Ethane is two carbon atoms, single-bonded together, with three hydrogens on EACH of those two carbon atoms.

Carbon atoms bring 4 valence electrons each – that makes 8 total valence electrons brought by carbon to this molecule. Hydrogen atoms bring 1 valence electrons each – that makes 6 total valence electrons brought by hydrogen. Therefore, we have 8+6 = 14 valence electrons to work with in this Lewis Structure.

Each of the single bonds in the molecule ‘uses up’ two electrons; that’s actually all of the electrons we are allotted; there are no “lone pairs” of electrons on this molecule.