Summary:
- By the year 1700, only a handful of elements had been identified and isolated.
- In 1829, a German chemist, Johann Dobereiner (1780-1849), placed various groups of three elements into groups called triads.
- English chemist John Newlands (1838-1898) ordered the elements in increasing order of atomic mass and noticed that every eighth element exhibited similar properties.
- Newlands’s work was largely ignored and even ridiculed by the scientific community in his day.
- It was not until years later that another more extensive periodic table effort would gain much greater acceptance.