Development of the Modern Periodic Table

The periodic table evolved over time as scientists discovered more useful ways to compare and organize the elements. 

Gases light, heat, dephlogisticated air, phlogisticated gas, inflammable air 

Metals antimony, silver, arsenic, bismuth, cobalt, copper, tin, iron, manganese, mercury, molybdena, nickel, gold, platina, lead, tungsten, zinc 

Nonmetals sulphur, phosphorus, pure charcoal, radical muriatique, radical fluorique, radical boracique  

Earths chalk, magnesia, barote, clay, siliceous earth 

You have already learned much in your study of chemistry. Wouldn t it be nice if you could easily organize the chemistry knowledge you are acquiring You can, with the help of the periodic table. It is called a periodic table because, much like the phases of the moon, one of which is shown in the chapter opening photo, the properties of the elements in the table repeat in a periodic way. The periodic table will be an invaluable tool as you continue this course in chemistry. However, before you learn about the modern periodic table, a recounting of the history behind the table s development will help you understand its significance. 

In the late 1790s, French scientist Antoine, Lavoisier compiled a list of elements known at the time. The list contained 23 elements. Many of these elements, such as silver, gold, carbon, and oxygen, were known since prehistoric times. The 1800s brought many changes to the world, including an explosion in the number of known elements. The advent of electricity, which was used to break compounds down into their component elements, and the development of the spectrometer, which was used to identify the newly isolated elements, played major roles in the advancement of chemistry. So did the industrial revolution 

A resident of London, England invented the word smog to describe the city s filthy air, a combination of smoke and natural fog. The quality of London s air became so poor that in 1952 about 4000 Londoners died during a four-day period. This incident led to the passage of England s Clean Air Act in 1956. 

John Newlands noticed that the properties of elements repeated in a manner similar to an octave on a musical scale (A, B, C, D, E, 

and so on). While there are some similarities between the law of octaves and the modern periodic table, there also are significant differences. You ll notice that some of the chemical symbols do not match. For example, beryllium (Be) was also known as glucinum (G). What similarities and differences can you identify  

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If there were a flag that represented the science of chemistry, it would be the periodic table. The periodic table is a concise organizational chart of the elements. The periodic table not only summarizes important facts about the elements, but it also incorporates a theoretical framework for understanding the relationships between elements. The modern periodic table attests to human s search for order and patterns in nature. As such, the periodic table is a dynamic blueprint for the basic building blocks of our universe. This chapter examines the development of the modern periodic table and presents information on how the modem periodic table is organized. 

What contribution did Moseley make to the development of the modern periodic table ... 

A historical perspective on the development of the modern periodic table is both interesting and important. A Russian chemist by the name of Dimitri Mendeleev is generally credited with the development of the first periodic table, although a German chemist, Lothar Meyer, working independent of Mendeleev at approximately the same time, did much the same work. Their... 

Development of the Periodic System Features of the Modern Periodic Table Atomic Structure and Elementary Periodicity Tabular Trends... 

When Mendeleev invented the periodic table, he was well-acquainted with Dalton s atomic theory. He knew nothing, however, about subatomic particles, and especially the electron, which is the foundation for the modern periodic table s distinctive shape. Because the original periodic table developed out of experimental observations, chemists did not need an understanding of atomic structure to develop it. (As you will see in section 3.3, however, the periodic table easily accommodates details about atomic structure. In fact, you will learn that the modern periodic table s distinctive design is a natural consequence of atomic structure.)... 

The second development that led to the modern periodic table was the acceptance of specific atomic masses for the elements. While today we readily accept the masses given in a periodic table, there was much... 

When a pure elemental gas, such as neon, was analyzed by a mass spectrometer, multiple peaks (two in the case of neon) were observed (see Fig. 1.11). Apparently, several kinds of atoms of the same element exist, differing only by their relative masses. Experiments on radioactive decay showed no differences in the chemical properties of these different forms of each element, so they all occupy the same place in the periodic table of the elements (see Chapter 3). Thus the different forms were named isotopes. Isotopes are identified by the chemical symbol for the element with a numerical superscript on the left side to specify the measured relative mass, for example °Ne and Ne. Although the existence of isotopes of the elements had been inferred from studies of the radioactive decay paths of uranium and other heavy elements, mass spectrometry provided confirmation of their existence and their physical characterization. Later, we discuss the properties of the elementary particles that account for the mass differences of isotopes. Here, we discuss mass spectrometry as a tool for measuring atomic and molecular masses and the development of the modern atomic mass scale. 

Relate historic experiments to the development of the modern model of the atom. Illustrate the modern model of an atom. Interpret the information available in an element block of the periodic table. 

The path of discovery of the elements belonging to the group termed rare earth elements was particularly confused and chaotic. It started 200 years ago, in 1787, and it closed in 1947 with the discovery of promethium. The rare earth elements cannot be properly and decently arranged in any of the numerous periodic tables of chemical elements developed since Mendeleev and Meyer, and though the modern... 

Dalton s little hard sphere model of the atom may seem primitive by today s standards, but it was an essential step in the evolution of chemical knowledge. Dalton s model persisted for almost one hundred years before anyone could think of any way to improve upon it. What is especially remarkable is that Dalton s theory was not completely accepted by the scientific community. Until 1900, there remained prominent physicists and chemists who continued to deny the existence of atoms. Actually, probably the most unsatisfying thing about Dalton s model is that it offered no explanation for the differences in chemical and physical properties that were observed among the elements. Even Dmitri Mendeleev, who, in 1869, developed the modern periodic table of the elements, could offer no explanation for the regular, or periodic, trends in the elements that were displayed in his periodic table. For that explanation, we must turn the clock forward to the events of the 1890s. 

Development of the Periodic Table The Modern Periodic Table... 

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