Hybridization of carbon atoms.

1. Single bonded tetrahedral C atoms: sp³ hybridization.

Summarized: One electron from the 2s orbital combines with the three electrons in the 2p orbitals to form four equal orbitals that point to corners of a tetrahedron. So the 3 in sp³ has nothing to do with a power of three, it represents the three electrons in the p orbitals p_x, p_y and p_z that are each containing one electron. Therefore we write sp³.

1.a. Draw the Lewis structures of the following species, molecules or ions. The central atom is underlined in most cases.	H2O2, CO2; H2O; CH3OH; CH3COOH; CH2F2; CO32-
1.b. Draw each species in its correct geometrical shape and write the name of the shape under it. In addition, write the approximate bond angle(s).
1.c. Explain for each of the molecules what attraction forces will hold them together as the substance is in its solid state.
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The trigonal planar C atoms, all C atoms with one double bond, sp² hybridization.

Summarized: One 2s and two 2p orbitals form three new orbitals that point to corners of a triangle, hence the trigonal planar shape. This occurs in tetrafluoroethene, C₂F₄ a starting compound for the manufacturing of teflon, the polymer that we use as the lineage in our frying pans and, by the way, C₂F₄ is one of the most slippery compounds we know.

The linear C atoms, all C atoms with a triple bond as in acetylene, C₂H₂, the gas used for welding. sp hybridization.

Summarized: one 2s and one 2p orbital form two new orbitals pointing to "opposite sides" of a line, hence the linear structure of acetylene. The remaining 2p_y and 2p_z orbitals form pi bonds through sideways overlap.


The step from ground state to excited state in which one electron from the 2s orbital jumps into the 2p_z orbital costs a little bit of energy, which could be delivered by light (e.g.). Forming bonds produces a great deal of energy, which offsets the energy needed for the 2s-2p jump shown here:

View the steps for each of the three hybridizations of carbon.

Click here for a tutorial page on hybridizations of carbon.

When you have gained enough experience with the concept of hydridization, you will understand that it is ultimately the bond angle that leads you to the type of hybridization carbon is in. Check out CO₂. Since the molecule is linear, the bond angle is 180⁰ and thus is carbon sp hybridized. Describe all the molecular orbitals (abbreviated M.O.'s) in CO₂, it is a good exercise.

Also, try to describe all the M.O.'s in dimethylacetylene.

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Here is a brief overview on the basics of  Electron Configurations

Electrons describe different types of orbitals in space. An orbital is a region in the space around the nucleus in which the chance to find the electron is 95%. We distinguish spherical shaped, dumbbell shaped and cloverleaf shaped orbitals. Electrons that go around the nucleus in a spherical shape are called s electrons and you may find them in the innershells of the elements in the first two vertical columns of the periodic table. The electron configuration of hydrogen is: H 1s¹ and for Helium He 1s², and for Lithium, Li 1s² 2s¹ etc. As soon as the 1s and 2s shells are full with 2 electrons the dumbbell shaped orbitals or p shells are filled up. Therefore the electron configuration of element number 5 boron is: B 1s² 2s² 2p_x¹. Realize that each orbital is completely filled when it contains 2 electrons. (This is the Pauli principle.)

There are three p orbitals, in the three orientations of the x, y, z coordinate system: p_x, p_y and p_z. These three orbitals are filled up first with a single electron and after that the second electron is coming in to pair up and completely fill them. The electron configuration of nitrogen is therefore:

N 1s² 2s² 2p_x¹ 2p_y¹ 2p_z¹

And for the oxygen electron configuration we then add one electron to the 2p_x orbital: O 1s² 2s² 2p_x² 2p_y¹ 2p_z¹. Neon is Ne 1s² 2s² 2p_x² 2p_y² 2p_z². For elements with an atomic number larger than neon we may write the electron configuration using the neon core, for example:

Mg [Ne] 3s² and Si [Ne] 3s² 3p_x¹ 3p_y¹. As long as you show (me) one time what the complete neon configuration is, you may use from that point on [Ne] as a short cut for the neon core. So far, we have used two principles to assign electrons to orbitals:

• The Aufbau principle. Aufbau is German for "build up". Electrons fill up the lowest energy orbitals first. They are closest to the nucleus, so first 1s, then 2s, then 2p, then 3s, followed by 3p etc.
• The Hund rule. Orbitals with the same energy, for example p_x, p_y and p_z are first filled up with a single electron.

To write configurations for elements in the fourth period of the Periodic Table we need to know that the 4s energy level is slightly lower than the 3d level. Then, using the two principles above for elements beyond calcium we can write the electron configuration of iron, ²⁶Fe: [Ar] 4s² 3d⁶. 

The 5s energy level is slightly lower than the 4d level, which will make the zirconium electron configuration: ⁴⁰Zr [Kr] 5s² 4d² . 

Thircool, butalwscheckm,toseeifthey'rite!

Practice writing the electron configurations in atoms of 16S; 27Co; 33As.

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