Johann Dobereiner of Germany in 1817 found that, if he took a triad of elements with similar properties, the atomic weight of the middle element is roughly midway between those of the other two [e.g., sodium with atomic weight 23 is midway between lithium (3) and potassium (39)
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Unknown title or logic that one can derive by looking at the similarity in the properties of certain classes of atoms (say, lithium, sodium and potassium) on one hand, and their atomic weights on the other? <span>Johann Dobereiner of Germany in 1817 found that, if he took a triad of elements with similar properties, the atomic weight of the middle element is roughly midway between those of the other two [e.g., sodium with atomic weight 23 is midway between lithium (3) and potassium (39), or bromine (80) between chlorine (35) and iodine (127)]. And in 1865, the English chemist John Newlands stated his “law of octaves”: if elements are arranged in increasing atomic weigh Summary
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