Hydrogen Bonding
Hydrogen bonding is a common “force” in nature, it’s what holds your DNA and proteins together and what makes water so weird and wonderful. Without it you wouldn’t be you, in fact you probably wouldn’t be anything. Hydrogen bonds are both inter and intra molecular forces in that it can act between different molecules (in the case of DNA bases) or within the same molecule (such as single chain proteins). Hydrogen bonding arises from polarity within a molecule, for this to happen a hydrogen must be bonded to an electronegative atom such as oxygen, fluorine or nitrogen (or be part of something like CHCl3). This causes the probability of an electron being around the hydrogen to decrease thus leaving it with a partial positive charge whilst the electronegative species has a slight negative charge. The slightly positive hydrogen is then attracted to other electronegative atoms that neighbor it. This causes an attractive force between them and gives an organized structure such as the crystalline form of ice or the hexagonal shape of a snowflake.
