Explore the fascinating wave nature of light in this 29-minute lecture from the Chemistry and Our Universe series. Delve into the historical debate over light's nature, tracing its origins from antiquity to the 19th-century triumph of wave theory. Discover how this understanding led to the revelation of the electromagnetic spectrum. Examine the crucial interactions between light and matter, learn to define key concepts like wavelength, velocity, and frequency, and witness Isaac Newton's groundbreaking demonstration of white light. Investigate Herschel and Ritter's discovery of invisible light, embark on a comprehensive tour of the electromagnetic spectrum, and tackle challenging problems relating wavelength and frequency. Gain valuable insights into the fundamental principles of chemistry and how they shape our understanding of the universe.