How are molecules of bonded atoms held together?Are ionic compounds just aggregates of oppositely charged ions and hence don"t have any definitive "molecules". What about molecules of covalently bonded atoms?
You are watching: What holds the atoms in a molecule together?
In non-nuclear smashville247.net, everything is electrostatic interactions. This is why you can learn and predict so much just by "following the electrons"
So the short answer to your first question is: "Molecular orbitals hold atoms together in covalent bonds, and those are a result of electrostatic interactions and the quantum nature of electrons."
In this picture, red means "more electrons" and blue means "less electrons." Water can form hydrogen bonds, which are very strong electrostatic interactions. Some atoms and molecules have an almost uniform charge density on the surface. We call these "non-polar" molecules - noble gases are good examples. However, even noble gases have what is called an induced dipole due to statistically correlated fluctuations in electron density when the atoms are near each other. As a result, even noble gases can be cooled to the point where they become liquid - the very, very weak electrostatic interactions will hold them together at low temperature, when they are not moving very fast. These forces are called London Dispersion Forces - after the guy who first described them. London dispersion forces are important, because they are found in all molecules - polar or not. In fact, this is what makes most plastics solid.
See more: How Many Ml In 2 Gallons Conversion (Ml To Gal), Convert Gallon To Ml
Polyethylene, for example, is made of very long chains of essentially non-polar molecules (from wikipedia):
Each chain is attracted to the others through weak London dispersion forces, however, since each chain has tens of thousands of atoms, those tiny forces quickly add up to make large forces holding the polymer together. This is why polyethylene is solid at room temperature, and can be used to make things like shopping bags!