Entropy (state of "disorder") of a closed system always increases, never decreases.
How can we then account for the formation of increasingly complex molecules needed for life from the so-called "primordial soup"? All other planets in Solar system follow this rule - very simple set of chemicals in their atmospheres, rarely anything more complex than basic inorganic stuff. Pretty much all organic molecules are associated with life - created by bacteria or other live organisms.
Can anybody explain this to me, please?
Quite simple really. The Earth is not a closed system. It is gaining energy from the Sun. Furthermore dust and meteorites are adding new solid material, organic compounds and other stuff from space all the time.