membrane leaflet

A phantom metaphor? An example of a metaphorically derived technical term which might be assumed by a novice or non-specialist to be a live metaphor,

"When phospholipids are exposed to water, they self-assemble into a two-layered sheet with the hydrophobic tails pointing toward the center of the sheet. This arrangement results in two 'leaflets' that are each a single molecular layer. The center of this bilayer contains almost no water and excludes molecules like sugars or salts that dissolve in water. The assembly process and maintenance are driven by aggregation of hydrophobic molecules (also called the hydrophobic effect). This complex process includes non-covalent interactions such as van der Waals forces, electrostatic and hydrogen bonds"

Wikipedia entry on Lipid bilayer

hydrogen bonds are like those you have with colleagues

An example of simile (and alternative conception) in popular science writing:

"Like relationships, compounds can be complicated and formed of different kinds of bond together. The best example is water, whose core compound [sic] is the product of two hydrogens (1 electron each) bonding covalently with an oxygen (6). But it doesn't stop there, because the hydrogens continue to be attracted to a neighbouring oxygen, forming additional ionic [sic] bonds – a combination known as hydrogen bonding. It's this mix of ionic and covalent that makes water one of the most versatile and accepting molecular mediators. Hydrogen bonds are akin to those you might have with work colleagues or teammates in sport: often not as strong as the connections with best friends or family, but essential bonds that can adapt to a wide variety of situations."

Dr Camilla Pang

Pang, C. (2020). Explaining Humans. What science can teach us about life, love and relationships. Viking.

Read about similes in science

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Note: This extract seems to confuse two features of bonding in water:

  • water has intramolecular bonding which is polar (primarily covalent with some ionic character) and which leads to a tiny proportion (about one in 10 000  000 at room temperature) of molecules being dissociated into hydrated ions {H+(aq), OH(aq)} . There is a dynamic equilibirum, which ions associating to form molecules at the same rate as other molecules dissociate.
  • There is also intermolecular hydrogen bonding which is discrete class of bonding (not covalent, not ionic).