The 2s² pair of carbon can be recoupled, which makes the usual tetravalence of carbon possible. Without recoupling, one might naively expect that carbon is divalent, since it only has two singly occupied 2p orbitals in its ground state 2s² 2p_x¹ 2p_y¹ valence electron configuration. There are states of CH and CH₂ that have covalent bonds that are consistent with this expectation. Doublet CH is the ground state of CH, but singlet CH₂ is the first excited state of CH₂. Here is the glyph of carbon indicating the coupled s-p lobe pair that is a better representation of the element than the glyph with a 2s² pair and unoccupied 2p orbital, along with the coupling diagrams for CH and CH₂ with covalent bonds:

There is a low-lying quartet excited state of CH where the lobe pair is recoupled (see below). In principle, the triplet ground state of CH₂ could involve (i) bonding H to the outer lobe orbital, which would yield a linear structure; (ii) bonding H to one of the off-axis 2p orbitals, which would yield a bent structure with a bond angle near 90° or (iii) a combination of the two, which would yield a bond angle between ~110° and 180°. The structure of triplet CH₂ has a bond angle of about 160° and is therefore consistent with the third scenario. The fourth glyph has a trefoil form with three in-plane s-p lobe orbitals that are 120° apart and a fourth out-of-plane unhybridized 2p orbital, as shown below.

When a third hydrogen atom is added to triplet CH₂ to form the doublet CH₃ methyl radical, there are again three options: (i) bond to the third in-plane lobe orbital to form a planar structure; (ii) bond to the out-of-plane 2p orbital to form a pyramidal structure; or (iii) a combination of the two, which would yield a flat pyramidal structure. In this case, the planar form is preferred. It is only when a fourth hydrogen is added that the planarity is broken, and the first three bond pairs bend back to make room for the fourth pair. That leads to tetrahedral methane, and the fifth, tetrahedral glyph. Coupling diagrams for CH₃ and CH₄ are shown here, along with the singly occupied 2p orbital on CH₃.

The linear motif glyph (quartet CH), planar motif glyph (doublet CH₂), and tetrahedral motif glyph (CH₄) can be used to construct coupling diagrams for tetravalent carbon-containing compounds. Examples that use the linear glyph include acetylene (C₂H₂) hydrogen cyanide (HCN), and carbon dioxide (CO₂).

Examples that use the planar glyph include ethylene (C₂H₄) and formaldehyde (H₂CO).

Finally, methanol (CH₃OH) is an example that uses the tetrahedral glyph:

In the next section, we will see that it is straightfoward to depict resonance forms with coupling diagrams.