Robert “Bob” Warren Chapman passed away in his sleep on January 21, 2021 in La Jolla, California due to a brain tumor. He was born May 30, 1951, in Staten Island, New York to Robert William Chapman and Portia Chapman née Mathews. Following his studies at Rensselear Polytechnic Institute on surface chemistry, Bob earned a Master of Science in Physical and Analytical Chemistry from Colorado University, performing his dissertation on atmospheric chemistry. He taught high school physics and chemistry in Aurora, CO, then went on to a three-decade career with the federal government. A highlight was his involvement in the formation of the Organization for the Prohibition of Chemical Weapons. During his lifetime, he travelled to over thirty countries for work and on holidays. In the summer of 2017, Bob retired to San Diego, CA where he volunteered at the North Clairemont Library, read books and scientific research papers, and played with his grandchildren. He is survived by his wife Helen, daughters Rhiannon (Scott Liker) and Jennifer Arnold (James Arnold IV) and son Robert Chapman, three grandsons James Arnold V, Logan Arnold, and Nathan Arnold; brother Bill Chapman and sisters Corinna Robert and Patty Kuehmann.