Mendeleev: periodic chart

Table 1,3 Mendeleev s periodic chart and electron configuration of elements. 

That Mendeleev was able to predict the properties of new elements helped convince many scientists of the accuracy of Dalton s atomic hypothesis. This in turn helped promote Dalton s proposed atomic nature of matter from a hypothesis to a more widely accepted theory. Mendeleev s chart, which ultimately led to our modern periodic table with its horizontal periods and vertical groups, also helped lay the groundwork for our understanding of atomic behavior and is recognized as one of the most important achievements of modern science. 

All the things we see and feel, even the air we breathe are altogether known as material. Through centuries of scientific investigation we have come to know and understand that all material is composed of atoms and atoms are in turn made up of nucleus and electrons. The number of electrons surrounding the nucleus defined as atomic number dictates the characteristic of that atom. There are more than 100 different types of atoms on earth and they are systematically arranged in Mendeleeve s chart, or known as the PERIODIC CHART OF THE ATOMS. ... 

In 1869, Dmitri Mendeleev was one of the first scientists to create a coherent arrangement of the elements. He did so by arranging elements in order of increasing atomic mass. He also created rows of elements that were arranged so that the vertical columns represented elements that shared similar characteristics. Much later, in 1913, Henry Mosely revised Mendeleev s chart so that elements were arranged by increasing atomic number rather than increasing atomic mass. This is the periodic table that you are familiar with today. Let s review the components and vocabulary associated with the modern Periodic Table of the Elements. 

Mendeleev made a prediction that the empty places in the periodic table stood for elements that had not yet been discovered. He said one could tell what those elements were going to be like by examining their position in the periodic table. For example, element number 21 would be like boron, Mendeleev predicted. Boron was the element above number 21 in Mendeleev s chart. He called the missing element (number 21) ekaboron, or similar to boron. ... 

For chemists working with several elements, the periodic chart of the elements is so indispensable that one is apt to forget that, far from being divinely inspired, it resulted from the hard work of countless chemists. True, there is a quantum mechanical basis for the periodicity of the elements, as we shall see shortly. But the inspiration of such scientists as Mendeleev and the perspiration of a host or nineteenth-century chemists provided the chemist with the benefits or the periodic table about half a century before the existence of the electron was proved The confidence that Mendeleev had in his chart, and his predictions based on it, make fascinating reading.16... 

Manganese [7439-96-5], chemical symbol Mn, atomic number 24, and relative atomic mass 54.938049(9), is the first element of group VIIB(7) of Mendeleev s periodic chart. Its name is derived from the Latin word magnes, owing to the magnetic properties of pyrolusite... 

Tin [7440-31-5], chemical symbol Sn, atomic number 50, and relative atomic mass 118.710(7), is the fourth element of group IVA(14) of Mendeleev s periodic chart. The symbol of the element was first introduced by Berzelius, who was inspired by the Latin word for the metal, stannum, while the name of the metal comes from the Old German word zinn and the Old Norse tin. Pure tin is a silvery-white malleable and ductile dense metal with a low melting point (231.928 C) and a high boiling point (2603 C). It exhibits a low electrical resistivity (4.60 p 2.cm) and a high thermal conductivity (227 Wm K ). Tin has two allotropes ... 

The alkali metals are represented by the six chemical elements of group 1A(1) of Mendeleev s periodic chart. These six elements are, in order of increasing atomic number, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The name alkali metals comes from the fact that they form strong alkaline hydroxides (i.e., MOH, with M = Li, Na, K, etc.) when they combine with water (i.e., strong bases capable of neutralizing acids). The only members of the alkali metal family that are relatively abundant in the Earth s crust are sodium and potassium. Among the alkali metals only lithium, sodium, and, to a lesser extent, potassium are widely used in industrial applications. Hence, only these three metals will be reviewed in detail in this chapter. Nevertheless, a short description of the main properties and industrial uses of the last three alkali metals (i.e., Rb, Cs, and Fr) will be presented at the end of the section. Some physical, mechanical, thermal, electrical, and optical properties of the five chief alkali metals (except francium, which is radioactive with a short half-life) are listed in Table 4.1. 

Strontium [7440-24-6], chemical symbol Sr, atomic number 38, and relative atomic mass (i.e., atomic weight) 87.62(1), is the fourth alkaline-earth metal, i.e., elements of group IIA(2) of Mendeleev s periodic chart. The word strontium comes from Strontian, a town in Scotland. Strontium is a hard, silvery-white metal when freshly cut, but it readily tarnishes in moist air, becoming yellowish due to the formation of the oxide. It resembles barium in its properties but is harder and less reactive. It has a low density (2540 kg.m" ), and a relatively... 

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