Students should use the Visual Elements: Development of the Periodic Table resource to answer questions about the role of the periodic table in the development of modern atomic theory. This sheet provides some answers to the questions they have on their Development of the Periodic Table student sheet.
In what sense did Mendeleev’s periodic table follow “a natural plan”?
He was able to see the natural arrangement of elements in terms of their similarities and recognized the appropriate places for elements that had yet to be discovered.
How does the periodic table classify elements today?
It is based on “the properties of atomic number of the nucleus and the electron energy levels which surround it.”
How was the work of Stanislao Cannizzaro significant in the development of the periodic table?
He was able to determine the exact atomic weight of elements, giving the table legitimacy over questionable “equivalent weights.”
What was de Chancourtois trying to accomplish with his “Telluric Screw”? What was its limitation?
He sought to reveal periodicity through atomic weights, but was unable to determine the frequency.
How were Newland’s findings both similar to and different from Mendeleev’s?
While Newland accurately arranged the elements in columns and ascending order based on weight, he failed to identify and make room for “unknown” elements still waiting to be discovered.
What does the early criticism of Newland’s Law of Octaves tell you about the nature of the international scientific community?
Any scientific claims that are published, whether ultimately accurate or not, undergo considerable scrutiny and debate. In Newland’s case, it took 18 years and much public criticism before his efforts were recognized.
How did Julius Lothar Meyer contribute to periodic development?
He created a periodic table that rivaled Mendeleev’s, but one year too late. His findings helped to confirm the principles underlying Mendeleev’s version.
What is unique about Mendeleev’s personal history?
Accept all answers. He endured an especially difficult upbringing only to go on to discover one of the fundamental laws of nature.
Why would Mendeleev (and other scientists) wish to arrange chemical elements in “a systematic way”? What was he (and others) ultimately trying to achieve and advance scientifically?
Accept all agreeable answers. One view is that Mendeleev and modern scientists in general look to identify and systematize areas of science to provide a concrete, factual infrastructure from which the laws and nature of science can be harnessed and applied for greater human use.
In what sense did Mendeleev discover “a fundamental pattern of nature”?
The natural relationship among elements and their properties has always been in existence; Mendeleev’s genius was the first to uncover these secrets of nature and reflect them in a table that humanity could use and benefit from.
What was truly groundbreaking about his work and methods?
Accept all reasonable answers. He foresaw and left “gaps” on his table for “missing” elements. He was strong enough to take critical risks, like placing elements in the “wrong” groups and in the order of atomic weight.
What is significant about the discovery of isotopes?
It accurately addressed weight anomalies and replaced atomic weights with atomic numbers as the first principle of Mendeleev’s periodic table.
What kinds of difficulties and errors did Mendeleev encounter in his work?
Accept all reasonable answers, from putting specific elements into groups to working with inaccurate atomic weights.
In what sense was Mendeleev (like all scientists) limited scientifically by the period in which he lived? How did he try to surpass these limitations?
Accept all agreeable answers. Mendeleev’s “struggle” accurately reflects the struggle of all scientists whose work and proposals are only as good as the ideas, tools, and technology available to them in their lifetimes and areas of expertise. In Mendeleev’s case, it seems he consciously sought to go beyond these natural limitations by predicting future discoveries and taking them into account prior to their discovery.