Chemistry is often described as the science of the invisible — atoms, bonds, and unseen reactions. But these microscopic processes shape some of the biggest challenges facing our world today. In this course, we link molecular-level processes to environmental, social, and policy issues, aiming to make the invisible scale of chemistry visible through its influence on the world around us. You will examine how the chemistry of the water molecule impacts public health and environmental justice; how the molecular structure of fossil fuels explains why they are a source of energy and their key role in climate change; and how essential elements like carbon, nitrogen, and oxygen come together to form complex biomolecules that enable life. Instead of seeing chemistry as just abstract equations, this class demonstrates its role in understanding and addressing real-world problems. Core chemical principles will be applied to explore: i) Why water’s molecular properties make it essential for life yet susceptible to contamination, and how this chemistry should guide safe and equitable drinking water delivery. ii) How a molecular understanding of fossil fuels explains their dominance in modern economies and their role as major sources of atmospheric carbon dioxide. iii) How life's elements come together to create proteins and nucleic acids, supporting biological complexity. Throughout the semester, you will learn to think across scales — from atoms to infrastructure, and from molecular interactions to policy. For the final project, you will use your chemistry knowledge to examine the global challenge of access to safe drinking water by analyzing drinking water treatment methods and drinking water policies.