The study of the elements goes back to ancient times. The work that led to the periodic table began during the Age of Enlightenment. At this time, people began conducting chemical experiments, which led to the discovery of new elements. Scientists continue to find elements and learn about them today. Below are some of the people whose work contributed to the formation of the periodic table.
The study of the elements goes back to ancient times. The work that led to the periodic table began during the Age of Enlightenment. At this time, people began conducting chemical experiments, which led to the discovery of new elements. Scientists continue to find elements and learn about them today.
Father of chemistry, Robert Boyle (image source Christianity.com)
Robert Boyle developed the definition of an element around 1650 that was used for 300 years. He defined an element as something that cannot be broken into smaller parts by a chemical reaction. Scientists used this definition until the discovery of subatomic particles.
Antoine-Laurent de Lavoisier
Antoine-Laurent Lavoisier (image source Britannica.com)
In 1789, Antoine-Laurent de Lavoisier wrote the Elementary Treatise of Chemistry. It was the first textbook devoted to chemistry. In it, he identified several new elements, including hydrogen, nitrogen and oxygen. He divided his elements into two groups, metals and non-metals.
John Newlands (image source: world cheemicals.com)
John Newlands published works in the early 1860s that divided 62 known elements into groups of eight. He was the first scientist to assign elements an atomic number, based on an element’s mass. He also paired elements with masses that differed by a factor of eight. Newlands work was not appreciated at the time, but today, he is credited with the first use of the term periodic in chemistry.
Dimitri Ivanovich Mendeleev
Dimitri Ivanovich Mendeleev (image source Scientist biography.com)
In the 1860s, three men independently published periodic tables: Dimitri Ivanovich Mendeleev, Lothar Meyer, William Odling. Mendeleev is credited with the development of the modern periodic table because his work was the most innovative and adaptable. His table not only documented known elements, but it also allowed space for the discovery of new ones. It had several interesting features:
• He speculated about the existence of undiscovered elements. Using a dash, Mendeleev left spaces in his table where he thought those elements should be placed.
• Mendeleev arranged his table by atomic mass. He also realised that elements with similar atomic masses had similar chemical properties.
• This helped him realise that some elements were in the wrong place when they were ordered by mass. He moved some elements, so they were beside elements with similar characteristics regardless of their mass.
• Mendeleev said an element’ properties could be predicted by using its mass and its position in the periodic table.
Mendeleev’s addition of dashes to his table was important for two reasons. One, it allowed for the addition of new elements and groups of elements he did not predict. Two, it would allow future scientists to adjust the position of elements within the table without damaging its integrity. Mendeleev later adjusted his table to correct the position of some elements.
Horace Groves Deming
Horace Groves Deming (image source: rootsweb.com)
In 1923, Horace Groves Deming published the 18-column periodic table that is common today. It was during the middle part of the 20th century that scientists discovered protons. Since then, the atomic number of an element has been based on the number of protons it contains.
Glenn T. Seaborg
Glenn Seaborg (image source Encyclopaedia Britannica)
During his work on the Manhattan Project, Glenn T. Seaborg began speculating that additions needed to be made to the periodic table. In 1945, he published a paper that said the actinide series of elements should be added to the periodic table as the second row of the f-block, below the lanthanide elements. Fellow scientists discredited his suggestion at first, but later research proved he was correct.
Since the 1940s, scientists have discovered the transuranic elements, numbers 104-118. The most recent of these was officially recognised in 2015. They completed the seventh row of the table. Little is known about some of these elements because they are unstable and decay rapidly.