Question About Methane Structure and Carbon Bonding


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Michelle_Nguyen_3F
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Joined: Wed Sep 21, 2016 2:59 pm

Question About Methane Structure and Carbon Bonding

Postby Michelle_Nguyen_3F » Fri Oct 28, 2016 12:27 am

Hello!
In the course reader on page 102, it says that that methane (CH4) structure has 4 equivalent covalent bonds that point towards the four corners of tetrahedron. It then says that carbon has only two unpaired electrons. Can someone explain that if C has only 2 unpaired electrons, how does it form 4 bonds? Also, can someone provide a simpler description of "4 equivalent covalent bonds that point towards the four corners of tetrahedron"? Thank you so much!

Noor_Chahal_3G
Posts: 18
Joined: Wed Sep 21, 2016 2:56 pm

Re: Question About Methane Structure and Carbon Bonding

Postby Noor_Chahal_3G » Fri Oct 28, 2016 1:29 am

When it says Carbon has 2 unpaired electrons, is referring to the fact that Carbon has an electron configuration of [He]2s22p2. Therefore Carbon has 2 unpaired electrons in the p sublevel.

To be able to form 4 bonds, Carbon forms a mixture of its valence electron orbitals, meaning the s and p orbitals combine to make a hybrid sp3

Now you have a total of 4 electrons (2 elecrtrons from 2s2, and 2 electrons from 2p2) and 4 orbitals (1 orbital from s, and 3 orbitals from p).

As a result, there is one electron for each of the 4 sp3 orbitals - allowing carbon to now form 4 bonds with hydrogen: CH4

MayaKhalil_1L
Posts: 34
Joined: Wed Sep 21, 2016 2:59 pm

Re: Question About Methane Structure and Carbon Bonding

Postby MayaKhalil_1L » Fri Oct 28, 2016 1:51 am

This is where hybridization comes in. Normally, C only has two unpaired electrons because its 2s orbital is full and its 2p orbital has two unpaired parallel electrons. However, a hybrid of these two orbitals forms 2sp^3 which combines the 2s and 2p orbitals and allows for each of the four electrons to occupy its own orbital. Since it has four unpaired electrons with this hybrid orbital, it can now form four bonds.

2s __ + 2p __ __ __ = 2sp^3 __ __ __ __

Second question: Since C is in the middle and there are 4 hydrogen atoms, all the bonds between them will be the same. Carbon is the middle with the four hydrogen atoms placed evenly around it, thus forming a tetrahedron. I'm not sure if that really answers your question or if it helps at all. What exactly about that statement confuses you?

I hope this helps(:


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