Mendeleev: The Periodic Table
What makes Dmitri Mendeleev special? Any student of science should be familiar with Mendeleev's name and research because he is considered the father of the periodic table of elements. Born in 1834 in Tobolsk Siberia, Dmitri Mendeleev was the youngest of seventeen children (sources vary on the number of children in the family). Mendeleev's father went blind and was not able to support the family anymore. Being unable to maintain financial needs, Mendeleev's mother started a glass factory that later burned down during Mendeleev's high school years. Mendeleev's mother decided that for Dmitri to be successful, he needed a college education. The political unrest during this time period made it extremely difficult for students outside of Moscow to be accepted at the university and therefore, Mendeleev was rejected. His mother, though, did not give up. A short period later, Dmitri and his mother left for St. Petersburg where she was determined to get him into a university program.
Dmitri took the university entrance exams and passed with such high honors that he was admitted into the science teacher training program on a full scholarship. He entered St. Petersburg University to study science in the fall of 1850. Mendeleev excelled in his academics despite being bed-ridden for a year and even earned the medal of excellence for being first in his class. Mendeleev later graduated at the ripe age of 22. Dmitri's career started here. He became a professor of general chemistry at the University of St. Petersburg and when he was unable to find the correct textbook for his class, he composed his own. Written between 1868 and 1870, Mendeleev's textbook provides the basis for many modern chemical theories including the periodic table of elements.
While writing The Principles of Chemistry textbook, Mendeleev arranged all of the 63 known elements by their increasing atomic weight. When he organized the table into horizontal rows, chemical patterns and properties started to emerge in each column. There obviously were gaps in the table and Mendeleev postulated that new elements would be discovered to fill these gaps. Since these undiscovered elements would belong to certain columns, he was able to predict the properties and bonding patterns of these unknown elements. Three of these unknown elements were discovered during his life—gallium (1875), scandium (1879), and germanium (1886). The discovery of these elements provided strong proof for Mendeleev's atomic theory and elemental grouping. In his Principles of Chemistry, Dmitri writes:
“I began to look about and write down the elements with their atomic weights and typical properties, analogous elements and like atomic weights on separate cards, and this soon convinced me that the properties of elements are in periodic dependence upon their atomic weights.” (The American Institute of Physics)
Mendeleev's table and his observations were presented to the Russian Chemical Society in March 1869 by his colleague (Mendeleev was ill at this time). Several other similar tables were presented within a short period of time, but Dmitri's contained the most research, thought, and organization. Some modern scholars say that Dmitri Mendeleev was one of the forerunners of the periodic law which states that, “when elements are arranged in order of increasing atomic number, elements with similar properties occur at periodic (regularly recurring) intervals.” (Stoker 57)
1). Brown, Theodore et.al. Chemistry. Englewood Cliffs: Prentice Hall, 2009. Pg. 256-257
2). Stoker, Howard. General, Organic, and Biological Chemistry. Boston: Houghton Mifflin, 2001. Pg. 57
3). "The Periodic Table of Elements." The American Institute of Physics -- Physics Publications and Resources. Web. 24 Nov. 2009. <http://www.aip.org/history/curie/periodic.htm>.