We present methods to sculpt light at the atomic and molecular scale to detect and control chemical transformations, en-route to improved planetary and personal health. First, we study plasmon-driven chemical transformations, focussing on the photocatalytic dehydrogenation of AuPd systems. Here, the Au acts as a plasmonic light absorber and Pd serves as the catalyst. Using optically-coupled electron microscopy, we find that plasmons modify the rate of distinct reaction steps differently, increasing the overall rate more than ten-fold. Plasmons also open a new reaction pathway that is not observed without illumination, laying a foundation for site-selective and product-specific photocatalysts. Next, we describe methods to enable enantiospecific photochemistry, using resonant dielectric nanoparticles. By overlapping electric and magnetic resonances, these nanostructures can significantly enhance circular dichroism for improved chiral sensing and spectroscopy as well as high-yield enantioselective photochemistry. Finally, we describe resonant nanophotonic surfaces that enable multiplexed detection of SARS-CoV-2 gene sequences. The high quality factor (high-Q) produces a large amplification of the electromagnetic field intensities near the nanostructures that increase the response to minute refractive index changes from targeted binding of nucleic acids; simultaneously, the optical signal is beam-steered for multiplexed detection. We will present the design and development of this quantitative optical assay, as well as application to clinical samples.