The Lewis Dot Structure for CH4

CH4 Lewis Structure
Created by MakeTheBrainHappy.
The Lewis Dot Structure for CH4 is shown above. These kinds of structures can also be shown by representing each of the bonds with two dots. Each atom in the bond has a full valence, with carbon having access to eight electrons and each hydrogen having access to two (this is why hydrogen only needs two). The covalent bonds between the C and the H are similar to the ones formed between two Hs because the relatively small difference in electronegativity between carbon and hydrogen.
Tetrahedral Structure of Methane
Methane is a tetrahedron structure in 3D space. Source
This Lewis Dot Structure also explains some of the fundamental properties of this particle. Since there are no lone pairs on the central atom (or any atom for that matter) there are few dipoles created and the minimal electronegativity difference means that these bonds can essentially be treated as nonpolar covalent bonds. This means that all attraction forces inside the molecule rely on weak London Dispersion Forces which only strengthen in far larger atoms. In fact the molar mass of Methane is so minuscule that it is sometimes mentioned as a possible lifting gas because its density is less than that of air. It boils at -161˚C due to the weak intermolecular forces present and normally exists as a colorless, odorless gas at STP (Standard Temperatures and Pressures).

Methane as a Solid
Methane in a Solid State. Source
Does Methane exist in other states?

Yes- it is theoretically possible to find methane in other states of matter (liquids, solids). But it is extremely rare. Solid Methane is found in hydrates which have trapped methane in a more solid state. Scientists have also theorized that the lakes of Titan, one of the moons of Saturn, are composed of Liquid Methane. Due to the low boiling and melting points, it is rare to find these other states present.

Is CH4 an acid or a base?

Methane does not really have classic characteristics of either an acid or a base but it has been classified as a very weak acid. It will not release a hydrogen in solution but it has been shown to release a hydrogen in low-pressure gas mixtures such as the upper atmosphere. However, it should be noted that all of the different species produced in these reactions are extremely unstable.

Is it soluble in water?

No- Methane is not soluble in water because it does not have polar/strong intermolecular forces needed to break the hydrogen-bonds found in water. Therefore is is classified as insoluble. However it is soluble in less polar solutions such as ethanol and acetone to a far greater degree.

Methane from a Gas Burner Stove
Methane from a gas burner stove. Source
How do Methane Emissions affect the Earth?

This article should have more information about to answer this question. A common statistic is that methane is a greenhouse gas 84 times more potent than CO2.

Methane Cycle Diagram
Methane Cycle. Source
What are the natural sources of CH4 (methane)?

There are a wide variety of sources that contribute to the cycling of methane within the earth. In terms of natural processes there are different microbes that will either release or take in methane to utilize for cellular metabolism. Most organisms as shown in the diagram are contributing methane to the environment. The imbalance within this cycle is caused by additional methane created through the burning of biomass and fossil fuels. Ultimately these agents react within the atmosphere to form power hydroxide ion oxidizers that are able to take a hydrogen from methane (CH4) - an incredibly difficult task as discussed before in this article in the section about methane as an acid.

Is CH4 polar or nonpolar?

We've written an entire article on whether CH4 is polar or nonpolar! Feel free to check it out at this address. As with all questions of polarity, the article examines the statement in terms of the geometric configuration and then tries to see how the varying electronegativities of the different elements impact the ultimate dipole moment. The existence of many elements with extreme electronegativities within one certain molecule can also have an impact!

Methane Cycle on Mars
Methane Cycle on Mars. Source
How else can be envision the methane cycle?

Scientists have postulated that the methane cycle is also taking place currently on Mars! Although it features different players due to the variable environment and different atmospheric composition, the same principle of sinks and releases are the same. Oftentimes it is postulated that methane is broken down into carbon dioxide and other alcohols instead of remaining as a free species in the atmosphere. For sinks it is most likely held as rock within the soil with the possibility of existing microbes either consuming and releasing methane into the atmosphere!