Definition of the word atomic weight

The term "atomic weight" was coined by the German chemist Johann Wolfgang Döbereiner in the early 19th century to describe the average relative mass of an atom of an element. He observed that certain elements, when arranged in groups of three, had similar properties and average atomic weights, leading to the concept of triads. Later, the French chemist Antoine-Laurent de Lavoisier contributed to the establishment of atomic weight by precise measurements of the mass ratios of elements in compounds. The modern concept of atomic weight is determined by the average mass of the naturally occurring isotopes of an element based on their abundances in nature, as proposed by the British physicist John Dalton. This concept is fundamental to chemical calculations and understanding chemical behavior, as atomic weight affects a variety of chemical properties, such as density, melting and boiling points, and reactivity.