The Development of the Periodic Table
The Development of the Periodic Table
Although Dmitri Mendeleev is often considered the ‘father’ of the periodic table, the work of many scientists contributed to its present form. Between 1817-1829, Johann Dobereiner began to group elements with similar properties in to groups of three or triads. This began when he noticed that the atomic weights of strontium (Sr) were halfway between Calcium (Ca) and Barium (Ba). He stated that nature contained triads of elements in which the middle element had properties that were an average of the other two elements. In 1863, John Newlands, an English chemist, proposed the Law of Octaves, which stated that elements repeated their chemical properties every eighth element. The musical analogy was laughed mocked at the time, but was found to be insightful after the work of Mendeleev and Meyer was published.
In 1867, Dmitri Mendeleev was teaching what we now call “General Chemistry” at the University of St. Petersburg. Since he didn’t like any of the available textbooks, he decided to write one of his own. When he arranged the elements in order of atomic weight, he found that the elements lined up naturally unto groups and families with similar properties. In 1869, Lothar Meyer published a preliminary list of 28 elements, and was the first to classify elements into 6 families according to their valence (The combining capacity of an element determined by the number of electrons that it will lose, add, or share when it reacts with other atoms). In 1894, Sir William Ramsay removed oxygen, nitrogen, water and carbon dioxide from a sample of air and was left with a gas 19 times heavier than hydrogen and very unreactive. He called this gas argon. He went on to discover more of what we know call noble gases, and was awarded the Nobel Prize in Chemistry in 1904. In 1913, Henry Moseley found a relationship between an elements X-ray wavelength and its atomic number. Moseley’s discovery showed that atomic numbers were not
Although Dmitri Mendeleev is often considered the ‘father’ of the periodic table, the work of many scientists contributed to its present form. Between 1817-1829, Johann Dobereiner began to group elements with similar properties in to groups of three or triads. This began when he noticed that the atomic weights of strontium (Sr) were halfway between Calcium (Ca) and Barium (Ba). He stated that nature contained triads of elements in which the middle element had properties that were an average of the other two elements. In 1863, John Newlands, an English chemist, proposed the Law of Octaves, which stated that elements repeated their chemical properties every eighth element. The musical analogy was laughed mocked at the time, but was found to be insightful after the work of Mendeleev and Meyer was published.
In 1867, Dmitri Mendeleev was teaching what we now call “General Chemistry” at the University of St. Petersburg. Since he didn’t like any of the available textbooks, he decided to write one of his own. When he arranged the elements in order of atomic weight, he found that the elements lined up naturally unto groups and families with similar properties. In 1869, Lothar Meyer published a preliminary list of 28 elements, and was the first to classify elements into 6 families according to their valence (The combining capacity of an element determined by the number of electrons that it will lose, add, or share when it reacts with other atoms). In 1894, Sir William Ramsay removed oxygen, nitrogen, water and carbon dioxide from a sample of air and was left with a gas 19 times heavier than hydrogen and very unreactive. He called this gas argon. He went on to discover more of what we know call noble gases, and was awarded the Nobel Prize in Chemistry in 1904. In 1913, Henry Moseley found a relationship between an elements X-ray wavelength and its atomic number. Moseley’s discovery showed that atomic numbers were not