Understanding how planets form and how they become habitable is at the forefront of astronomical research and is of great public and scientific interest. When stars form they are surrounded by an orbiting disk of gas and dust which, are the building materials of planets (see schematic in Fig1). Approximately 20 different molecules have been detected in protoplanetary disks to date. By studying these disks with Atacama Large Millimetre Array (ALMA) we can map the spatial distribution of gas and dust with unprecedented detail. There now is ever-growing evidence for the presence of planets in disks (e.g. the rings of dust in HL Tau and HD 163296). I focus on detecting simple molecules in these planet-forming (and planet-hosting) disks and using them as diagnostic tools to understand the physical conditions associated with planet formation.