Historical Development and Current Structure
The first scientific discovery of an element was in 1649 by Hennig Brand who discovered phosphorus.The first scientific discovery of an element was in 1649 by Hennig Brand who discovered phosphorus. By 1869, a total of 63 elements had been discovered.By 1869, a total of 63 elements had been discovered. As the number of known elements grew, scientists began to recognize patterns in their properties and began to develop classification schemes.As the number of known elements grew, scientists began to recognize patterns in their properties and began to develop classification schemes.
1860 Dmitri Mendeleev began thinking about how he could organize the elements based on their physical and chemical properties.1860 Dmitri Mendeleev began thinking about how he could organize the elements based on their physical and chemical properties. Mendeleev liked card games so he made a set of card with each element on it and spent hours trying to arrange the cards into a pattern.Mendeleev liked card games so he made a set of card with each element on it and spent hours trying to arrange the cards into a pattern.
He figured out a way to organize the elements using the properties of the elements on the cards.He figured out a way to organize the elements using the properties of the elements on the cards. –Instead of similar suits (heart, spade, etc) he did similar properties –He used increasing atomic mass-the average mass of all the element’s isotopes. Mendeleev produced the first periodic table of the elements in 1869.Mendeleev produced the first periodic table of the elements in 1869.
Henry Moseley, a British Physicist, was able to determine by 1914 the atomic numbers of all the known elements using an experimental technique.Henry Moseley, a British Physicist, was able to determine by 1914 the atomic numbers of all the known elements using an experimental technique. Moseley then proceeded to rearrange the elements according to increasing atomic numbers.Moseley then proceeded to rearrange the elements according to increasing atomic numbers. Moseley's periodic law is now considered the current Periodic Law.Moseley's periodic law is now considered the current Periodic Law.
Glenn Seaborg, an American chemist discovered plutonium in 1940.Glenn Seaborg, an American chemist discovered plutonium in He discovered all the special state transition metal elements from 94 to 102 in the 1950’s.He discovered all the special state transition metal elements from 94 to 102 in the 1950’s. He reconfigured the periodic table by placing the actinide series below the lanthanide series.He reconfigured the periodic table by placing the actinide series below the lanthanide series.
Mendeleev MoseleySeaborg
The elements are arranged in increasing order of atomic number as you go from left to right across the table.The elements are arranged in increasing order of atomic number as you go from left to right across the table. The horizontal rows are called periods; there is a progression from metals to non- metals across each period.The horizontal rows are called periods; there is a progression from metals to non- metals across each period. The vertical rows are called groups or families; elements in each group share similar physical and chemical properties.The vertical rows are called groups or families; elements in each group share similar physical and chemical properties.
Examples of elemental families - Alkali metals (1); Alkaline earth metals (2); noble gases (18).Examples of elemental families - Alkali metals (1); Alkaline earth metals (2); noble gases (18). Transition metals: Similar in many ways, they are often used as catalysts.Transition metals: Similar in many ways, they are often used as catalysts. Lanthanides: (Elements 58 to 71) are found on earth in only very small amounts.Lanthanides: (Elements 58 to 71) are found on earth in only very small amounts. Actinides: (Elements 90 to 103) include most of the well known elements which are found in nuclear reactions.Actinides: (Elements 90 to 103) include most of the well known elements which are found in nuclear reactions.
The elements with larger atomic numbers than 92 do not occur naturally. They have all been produced artificially by bombarding other elements with particles.The elements with larger atomic numbers than 92 do not occur naturally. They have all been produced artificially by bombarding other elements with particles. What is the Periodic Table of The Elements? "It is a huge, efficient resource!"
Read pages 150 and 151. What are the trends in the periodic table?Read pages 150 and 151. What are the trends in the periodic table? Answer questions 1-6 on page 151 in your journal.Answer questions 1-6 on page 151 in your journal.