ChemDuet 1.6.2 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This Mac application is a product of Synergy Creations. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. ChemDuet for Mac lies within Education Tools, more precisely Science.
From the developer:
ChemDuet is the premier chemistry reference tool for your iPod. ChemDuet gives you quick access to atomic properties, wherever you go with your iPod. The included data is based on Synergy Creations' award-winning Periodic Table software. Easily adjust units of properties stored on iPod.
You may want to check out more Mac applications, such as sciatrope, Analytics to Earth or TreeView X, which might be related to ChemDuet.