Hydrogen Bonds
Let´s start out by saying that hydrogen bonds are quite weak bonds (1/10th of a covalent bond) that happen between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Most of the time the atom with a partially negative charge is oxyen, nitrogen, or flourine, and logically the partially positive atom is hydrogen.
Water is a perfect example: each water molecule can potentially form four hydrogen bonds with surrounding water molecules. And thanks to the fact that there are
exactly enough hydrogen and lone pairs so they can all
be hydrogen bonded.
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