The purpose of this lesson is to introduce and focus on the early history of the periodic table. Students should use information from A Brief History of the Development of Periodic Table to complete a timeline. This sheet provides key dates, facts, figures, and events for the timeline. The answers to the remaining questions can be found in the body of the lesson.
Periodic Table Timeline
Students should fill in the blanks with the correct dates, facts, and figures.
1649 — Hennig Brand discovered phosphorus.
1829 — Johann Dobereiner discovered the halogen triad and the alkali metal triad.
1862 — The first periodic table was created by de Chancourtois. He assembled the table by
classifying chemical elements in an order based on their periodicity of chemical and
1864 — John Newlands published his own version of the periodic table and developed the Law
1869 — Dmitri Mendeleev published his periodic table, eventually becoming the “father of the
1870 — Lothar Meyer published his version of the periodic table (after Mendeleev).
1895 — Lord Rayleigh discovered argon, a new gaseous element that was chemically inert.
1898 — William Ramsey helped to establish the “zero” group (for “zero valency”) and predicted
the future discovery of the element neon.
1911 — Ernest Rutherford established that “the nuclear charge on a nucleus was proportional
to the atomic weight of the element.”
1911 — A. van den Broek established that the atomic weight of an element was approximately
equal to the charge on an atom. This charge became the “atomic number” by which
periodic table elements are classified.
1913 — Henry Moseley discovered the isotopes of elements. This discovery established that
“the properties of the elements varied periodically with atomic number,” not atomic
weight, which had been previously accepted under periodic law.
1940 — Glenn Seaborg discovered plutonium and the transuranic elements from 94 to 102.
His findings represented the last (and most recent) changes to the periodic table.
This teacher sheet is a part of the The History of the Atom 3: The Periodic Table lesson.