Atoms, elements, molecules... What's the difference? This is part 3 in the Stated Clearly series: An Introduction to Chemistry. In it you will find a simplified definition of a molecule, you will learn how we model molecules, and you will see actual images of real molecules and their vibrational modes!

You can play the Bond Breaker game at https://testtubegames.com/bondbreaker3.html

You can support this channel at https://www.patreon.com/statedclearly

MORE ON OUR DEFINITION OF A MOLECULE

This definition is great because it's so easy to make sense of, but there are some problems with it. Biologists will sometimes consider a double stranded chain of DNA to be a "single molecule", even though each half of the strand is bound to the other via non-chemical hydrogen bonds. The same is true for some protein complexes composed of multiple sub-units.

Alternatively, some crystals (such as quartz) are made of repeating patterns of atoms all chemically bound. Using our definition, you'd have to consider an entire quartz crystal to be a "single molecule". Chemists don't usually do this, instead they consider each repeating sub-unit to be a molecule. Pure metals have a similar issue.

Language is a living, evolving mess! Even in formal scientific fields where you might expect more consistency.

MORE ON HYDROGEN MOLECULE FORMATION

To avoid distraction when teaching the basic concept of a molecule, we chose to ignore this technicality in the animation. You can read here about how hydrogen molecules normally form in space: https://www.sciencedirect.com/science/article/pii/S2405675817300271

PAPERS DISCUSSED IN THIS ANIMATION

Here is the molecular image by Leo Gross at IBM in 2009: https://www.researchgate.net/publication/26773422_The_Chemical_Structure_of_a_Molecule_Resolved_by_Atomic_Force_Microscopy

Here is the paper on molecular vibrations by Joonhee Lee in 2019: https://www.nature.com/articles/s41586-019-1059-9

Arabic CCs by Mustafa Farqad