In nature, many atoms exist in a bound form, forming special associations called molecules. However, inert gases, justifying their name, form monatomic units. The molecular structure of a substance usually implies covalent bonds. But there are also so-called conditionally weak interactions between atoms. Molecules can be huge, consisting of millions of atoms. Where is such a complex molecular structure found? Examples are many organic substances such as quaternary proteins and DNA.
No chemicals
The covalent bonds that hold atoms together are extremely strong. But the physical properties of a substance do not depend on this, they depend on van der Waals forces and hydrogen bonds, which ensure the interaction of neighboring fragments of structures with each other. The molecular structure of a liquid, gas or low-melting solid substances also explains the state of aggregation in which we observe them at a certain temperature. In order tochange the state of matter, just heat it or cool it. Covalent bonds are not broken.
Borders for the start of processes
How high or low will the gassing and melting points be? It depends on the strength of intermolecular interactions. Hydrogen bonds in a substance increase the temperature of the change in the state of aggregation. The larger the molecules, the more van der Waals interactions they have, the more difficult it is to make a solid substance liquid or liquid gaseous.
Features of ammonia
Most known substances are not soluble in water at all. And those that do dissolve, interact, often with the formation of new hydrogen bonds. An example is ammonia. It is able to break hydrogen bonds between water molecules and successfully build its own. In parallel, an ion exchange reaction takes place, but it does not play a big role in the dissolution of ammonia. Ammonia owes this process mainly to hydrogen bonds. The reaction goes both ways, the process can generally be in equilibrium at certain temperatures and pressures. Other soluble substances, such as ethanol and sugars, also bind well with water through intermolecular interactions.
Other reasons
Solubility in organic liquids is provided by the formation of van der Waals bonds. In this case, the intrinsic interactions of the solvent are destroyed. The solute binds to its molecules, forming a homogeneous-looking mixture. Many life processes have becomepossible due to these properties of organic substances.
Toku - no
Why don't most substances conduct electricity? The molecular structure does not allow! The current requires the simultaneous movement of a large number of electrons, a kind of "collective farm" of them. This happens with metals, but it almost never happens with non-metals. On the border with respect to this property are semiconductor materials that have a medium-dependent electrical conductivity.
Very many physical processes can be easily explained if there is information about the molecular structure of a given substance. Aggregate states are well studied by modern physics.
