Electron/atom
Electrons travel at 1/300th speed of light
An electron is a minute particle, estimated to be 1 millionth of a billionth the size of a gnat*.
As objects get smaller, they move faster.
While fast flying insects can travel at speeds of 15 m/s (meters/second), a hypothetical electron will have a speed of 2,200 km/s (~ 5 million mph): 150,000 times faster.
In a vacuum, electrons have been measured to travel at the rate of 1,000 km/s (~2.2 million mph). Whatever number you use, there is no escaping that electrons travel very fast.
*no-see-ums are 1mm in size; electrons are estimated to have a radius of 10^-18 m. Thus, one electron is about 1/10^15th of a gnat.
The electrons are moving even in molecules
Let's take a group of molecules, like in a piece of metallic sodium. The electrons in the outer shell of each sodium atom (the valence electrons) are continuously moving. Consider a stack of such atoms. Each sodium atom's lone 3s electron is traveling in between the nuclei at 1,000 km/s!
At any one time, each of those electrons is attracted to one of the sodium nuclei close to it; then it gets attracted to a different nucleus, and then a third. The combination of continuous motion as well as the attraction to multiple positive nuclei create a sea of electrons surrounding the sodium nuclei.
sodium metal bonding
The electrons act as if they have speed dating apps, allowing them to quickly change which nucleus they are attracted to. As one can imagine, given the innumerable electrons and nuclei, there is a lot of juggling going on: connections are being broken and reformed almost instantaneously.
A chunk of sodium seems to have solved how to get atoms to attach to each other even though the electrons are never still; it does this by having communal attraction between the electrons and all the nuclei.
Placing two atoms together to create a molecule
How do other atoms create solid bonds? In a hydrogen molecule, there are two electrons that are very mobile. Yet they create a sigma (σ) bond, where two electrons seem to park themself between the nuclei.
How do the two hydrogen atoms have their electrons stay in one place long enough to make a connection? It would be like asking the cars on a NASCAR racetrack to slow down when they reach certain positions on the track so that one could take a non-blurred image of each car.
That is what electrons seem to do. Even while traveling insanely around the nucleus, electrons seem to have favorite positions that they rest in more often than others, both in space and time.
It is this ability of electrons to "stay parked" in certain places that creates solid bonds between atoms.
References:
- Covalent bonds. https://courses.lumenlearning.com/boundless-chemistry/chapter/the-covalent-bond/
- Atomic orbitals and covalent bonding. https://chem.libretexts.org/Courses/Purdue/Purdue%3A_Chem_26505%3A_Organic_Chemistry_I_(Lipton)/Chapter_1._Electronic_Structure_and_Chemical_Bonding/1.07_Atomic_Orbitals_and_Covalent_Bonding
Picture credits:
- Kevin Dooley. Atom: Protons, Neutrons, Electrons, Probability, taken on Dec 7, 2013.
- By adison pangchai. Model of Abstract Atom Structure. Vector illustration. ID: 550452931.
- By Emre Terim. Chemistry - Formation of metallic bond. ID: 1440912644.
- Hijab, j. H2 molecule electron positions, uploaded Jan 2020.