Period

Periodic The Table 1 Lavoisier Made the first list of 30 substances he thought were elements D?bereiner Created a list of elements based on triads triads: groups of 3 elements with similar properties Created a list of elements based on triads problem with triads: Soon more elements were found; there were more than 3 similar elements to a group. D?bereiner periodicity repetition of a property on a regular basis Newlands Arranged elements by atomic mass Observed the ?law of octaves? Every 8th element repeats properties. Included the transition metals Mendeleev Developed the periodic table by arranging elements by atomic mass (like Newlands) Included the transition metals (like Newlands) Mendeleev Left blanks when properties or mass did not fit