Theodore William Richards

Theodore William Richards was an American chemist whose precise measurements of atomic weights helped establish reliable values for chemical elements. He received the 1914 Nobel Prize in Chemistry.

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Atomic weight: The weighted average mass of an element’s atoms relative to a specified standard. His painstaking measurements made atomic weights more accurate and dependable.
Gravimetric analysis: A quantitative method that determines a substance’s amount by measuring its mass. Richards used carefully weighed chemical compounds to infer elemental proportions.
Josiah Parsons Cooke: An American chemist and Harvard professor who helped establish chemistry at Harvard. Cooke taught Richards at Harvard and shaped his early scientific training.
Atomic mass unit: A unit of mass defined as one-twelfth the mass of a carbon-12 atom. Atomic masses require a shared unit and reference scale for comparison.
Atomic weight of oxygen: The relative average mass assigned to oxygen atoms on an atomic-weight scale. Oxygen measurements formed part of the careful comparative work associated with Richards.
Nobel Prize in Chemistry: An annual international award recognizing major contributions to chemistry. Richards received the 1914 prize for his atomic-weight determinations.
Silver coulometer: An electrochemical instrument that measures electric charge through the mass of deposited silver. It provided a precise route to comparing electrochemical and chemical quantities.
Harvard University: A private research university in Cambridge, Massachusetts, founded in 1636. Richards studied and carried out much of his research at Harvard.
Law of definite proportions: The principle that a pure chemical compound contains elements in fixed mass proportions. Richards’s analyses relied on compounds having reproducible elemental ratios.
Atomic weight of silver: The relative average mass assigned to silver atoms on an atomic-weight scale. Silver compounds offered especially useful material for precise gravimetric measurements.