100 Nano-Stories: Sigma & Pi Orbitals Explained!
Episode #43: 2sp3, 2sp2, 2sp, And More!
Preface! ✨
It’s your favorite material science & nanotechnology enthusiast! A couple of days ago, I explained hybridization in its entirety, and I recommend reading the article before proceeding. Otherwise, you would not have a clue about what I am talking about. Don’t worry, the article is only 3 minutes long! 😉
But for today’s topic, let’s discuss more on the hybrid orbitals! Specifically, let’s discuss the S orbitals & P orbitals in Carbon atoms! Knowing this will be essential to our further research on polymer aerogels and more importantly. . . my personal idea for aerogel technology! 🤫
But anyway, let’s go! 😤
Hybrid Orbitals Explained! 💡
Fundamental Concepts! 🔑
Unhybridized Orbitals in Carbon Atoms will make Pi bonds (π). Pi bonds occur from an overlap of unhybridized “P” orbitals.
Hybridized Orbitals in Carbon Atoms will make Sigma bonds (σ). Sigma bonds occur from an overlap of hybridized “S” orbitals.
S → Sigma Orbital.
P → Pi Orbital.
An “S” Orbital looks like a circle. It is a circle because all of the electrons in that orbital are filled. (In the case of a carbon atom, we are looking at the 2nd orbital, the 2s orbital, 1 of the 4 valence electrons in a carbon atom).
A “P” Orbital is a little bit different. There are 3 ways “P” orbitals can be found. They can be found on the x-axis, y-axis, or z-axis. (In the case of carbon, we are looking at the 2nd atomic orbital, the remaining 3 of the 4 valence electrons in a carbon atom.)
Carbon Bonding (S & P Orbitals)! 🔑
So, if a carbon atom has one “S” orbital and three “P” orbitals in its second electron shell (outer electron shell), it would need to bond with four other atoms to get the energy level of all 4 valence electrons to be the same.
When this happens, the valence electron energies are all hybridized (or combining electron energies). Because of this bonding with 4 other atoms, the “S” and “P” orbitals are gone. Instead, we have four 2sp3 orbitals (hybrid orbitals).
But Carlos, what does “2sp3” mean?
Definition of “2sp3” means this:
- “2” → The 2nd energy level (or electron orbit/shell) that the valence electrons are located in the carbon atom.
- “S” → The “S” orbital that contributed to the hybridization of the carbon atom.
- “P” → The “P” orbitals that contributed to the hybridization of the carbon atom.
- “3” → The number of “P” orbitals that contributed to the hybridization of the carbon atom.
This happened because of two reasons:
- The combination of one “S” Orbital and three “P” Orbitals.
- The bonding of 4 other atoms with the carbon atom and their electrons to form hybrid orbitals.
Alkanes, Alkenes, And Alkynes! 🔑
So how can this help us with an alkane, an alkene, and an alkyne?
In an alkane, all of the “P” orbitals will become hybridized. Because it’s an alkane (single bonds only), this will result in only sigma bonds in the molecule.
In an alkene, one of the three “P” orbitals will not hybridize. In an alkene, there are double bonds, and in a double bond, we will have a sigma bond and a pi bond. The remaining unhybridized “P” orbital will become a pi bond, while the hybridized “P” orbitals will become sigma bonds.
In an alkyne, two of the three “P” orbitals will not hybridize. In an alkyne, there are triple bonds, and in a triple bond, we will have a single bond and two pi bonds. The two unhybridized “P” orbitals will become pi bonds, while the remaining hybridized “P” orbital will become the sigma bond.
Closing Thoughts! 💭
Reader, this is how I feel after writing this article because there was so much information to condense:
But going back to serious mode, if there is anything that I didn’t clarify well enough or if there is something that I missed, please let me know! I will do my best to clarify it for you!
See you tomorrow for a lesson and clarification on psi (pound per square inch) during the supercritical drying of aerogels! 👋🏽
Vocabulary! 📓
Sigma Bonds → Head-to-head overlap of atomic orbitals. The symbol for sigma is (σ).
Pi Bonds → Lateral overlap of atomic orbitals. The symbol for pi is (π).
Hybridization → Combining two things to make one new thing.
Valence Electrons → Electrons in the outer shell/last row of an atom.
S → Sigma Orbital.
P → Pi Orbital.
Alkanes → Single Bonds that occur between carbon atoms in a molecule in organic chemistry.
Alkenes → Double Bonds occur between carbon atoms in a molecule in organic chemistry.
Alkynes → Triple Bonds that occur between carbon atoms in a molecule in organic chemistry.
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© 2021 by Carlos Manuel Jarquin Sanchez. All Rights Reserved.
