I understand that the sodium and chlorine in an individual NaCl molecule are bonded ionically, but how are the molecules in a crystal containing millions of these molecules bonded to eachother?
I'm confused because since the difference in charge between the Na and Cl in each molecule are "canceled" by the ionic bond, why do they still bond to other molecules of NaCl? Wouldn't they just "slide" over each other and not bond
[OP] I understand that the sodium and chlorine in an individual NaCl molecule are bonded ionically, but how are the molecules in a crystal containing millions of these molecules bonded to each other?
There are no molecules in a NaCl crystal. That is, there is no specific chloride neighbor that a sodium ion "belongs to".
[OP] I'm confused because since the difference in charge between the Na and Cl in each molecule are "canceled" by the ionic bond, why do they still bond to other molecules of NaCl? Wouldn't they just "slide" over each other and not bond
The "cancellation" is true for dipoles (e.g. HCl) at large distances. However, if you come close enough, the two atoms in HCl still have positive and negative charges (partial charges in this case, because HCl forms covalent rather than ionic bonds).
[OP in comments] I understand that one sodium cation can ionically bond to one chloride anion, but how can one chloride anion bond to six sodium cations? If the Na+ has taken an extra electron from a Cl-, doesn’t that mean that that particular Cl- has no extra electrons left over to give? So how does it give an electron to six Na+’s in order to ironically bond to them?
Ionic bonding is sometimes explained has moving an electron from the metal to the non-metal. However, you can also form an ionic crystal from pre-formed ions, for instance from a sodium chloride solution where individual ions are surrounded by water. So the sodium has no need to give away 6 electrons, it just has to approach 6 anions.
It turns out that a chloride ion has plenty of space around it to accommodate 6 sodium ions. There is some repulsion between those sodium ions, but this is offset by the stronger attraction between unlike ions (the attraction is stronger because unlike ions at closer distance than like ions).
NaCl is explained here: http://hyperphysics.phy-astr.gsu.edu/hbase/molecule/NaCl.html The separated ions are unstable with respect to the separated atoms because the ionization potential of Na is greater than the energy supplied by the electron affinity of Cl. The approach forming a highly ionic-covalent bond forms what seems to be a stable molecule in the gas phase. Stable but very reactive because it is almost exposed ions. If a solid or liquid or solution phase is formed additional energy is released by attractions of the exposed ions with ions or dipoles of the opposite charge. These lattice energies, well defined and regular in the crystal, fluid in the melt, and solvation energies in solution are very large for ions because they spread the charge over several ions. For less ionic, less polar or nonpolar compounds the interparticle or intermolecular forces are less energy releasing so molecular integrity is maintained in the liquid and solid; there are some exceptions in solutions for compounds such as the strong acids.
In an NaCl crystal, the sodium ions (Na+) and chloride ions (Cl-) arrange themselves in a repeating, three-dimensional lattice structure. When one electron from sodium is transferred to chlorine, an electric force between the sodium and chlorine ions holds the NaCI molecule together. Each Sodium ion is surrounded by 6 chloride ions, and each chloride ion surrounded by 6 sodium ions in a lattice stucture. These crystals are hard yet brittle due to the regular lattice structure of the ions which can slide and break.
I would suggest you to watch this video for more clarification: https://www.youtube.com/watch?v=csfOBynrF8E
Also check this out: http://www.ilpi.com/inorganic/structures/nacl/index.html#:~:text=NaCl%20has%20a%20cubic%20unit,has%20a%20local%20octahedral%20geometry.
