"Sigma bonds occur when s orbitals, p orbitals pointing along the axis to the other bonding atom, or hybridized orbitals collide and overlap; the region of maximum electron density is between the two bonded atoms and lies along the axis between them. Single-order bonds are always σ bonds. Sigma bonds are like taking the index finger from each hand and pointing them directly at each other, so one fingertip touches another. Just as you can rotate your fingers without losing contact, bonded atoms can rotate freely about a sigma bond."
"Sigma bonds are like the collision of two raindrops, with one falling from the earth toward the sky, just before the integrity of both would be shattered by impact. The magnificence and beauty, is nothing short of stunning."
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.