These numbers are the cause of periodicity in properties due to the repetition of similar electronic configuration. Roger the Mole. actinides. Prediction of errors : This periodic table could predict errors in the atomic masses of some elements on the basis of their position in the periodic table. Each group is an independent group and the idea of sub-groups as in the case of Mendeleev’s periodic table has been discarded. The key difference between Mendeleev and Modern periodic table is that the basis of the modern periodic table is mainly the electronic configuration of the elements, which we call as the atomic number whereas, in Mendeleev periodic table, it is the atomic mass of the elements. The modern periodic table explains why periodicity in properties of elements exists. Groups 1, 2 and 13 to 17 are called normal elements. Ans. The atomic number is the number of protons in an atom of an element. Modern Periodic Table has seven (7) horizontal rows called periods. A modern periodic table arranges the elements in increasing order of their atomic numbers and groups atoms with similar properties in the same vertical column ( Figure 2 ). That’s the positive charge of the nucleus. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Each square shows the chemical symbol of the element along with its name. Therefore, the bottom-left most element (francium) is predicted to have the lowest electronegativity and the top-right most element (fluorine) is predicted to have the highest electronegativity. Since the properties of an element depend on its electronic configuration, thus electronic configuration of elements is intrinsic to the Modern Periodic Table. However, this method was not without fallacies as it didn’t take into account the atomic masses of the elements. The elements present in a group have the same number of electrons in the valence shell of their atoms. (iv) The element in period 3 which forms ions with -2 charge is … The modern periodic table clarifies why elements in a group show similar properties but elements in different groups show different properties. Groups: Henry Moseley, a physicist from England in the year 1913, observed that when certain metals were bombarded with high-speed electrons, X-rays are emitted. Thus, we can easily know the properties of other elements of a group if we know the properties of even two elements of the same group. The periodic table is one of the cornerstones of chemistry because it organizes all the known elements on the basis of their chemical properties. Explanation of the Modern Periodic Law on the Basis of Electronic Configuration: In chemical reactions, there is a transfer or sharing of electrons. In 1789, Antoine Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths. For example, the three isotopes of hydrogen i.e. Elements of group 16 are called chalcogens [ore forming elements]. in modern periodic table, the elements were classified on the basics of the increasing order of their atomic number. November 28, 2020 Alkali metals are monovalent elements because they tend to lose the valency electron during the chemical reaction . Similarly, physical properties of an element are dependent on the configuration of electrons in an atom of the element. Elemental life cycle analyses yield an understanding of these materials, and a definite concern that arises is that of possible scarcity of some of the elements as their use … These numbers are called magic numbers. The periodic table correlates the position of an element with its electronic configuration. The elements of these series are called Lanthanoids and Actinoids. Russian chemist Dmitry Mendeleev is credited with developing the basis for the modern periodic table in 1869. Basis of the Modern Periodic Table. (ii) The gaps left in the periodic table helped in the discovery of unknown elements. When Mendeleev first put together the periodic table it was based on similarities in the chemistry of the elements, as the elements were ordered by … The positions of certain elements which were earlier misfits in Mendeleev’s periodic table are now justified because it is based on an atomic number of the elements. Group 18 or 0 contains noble or inert gases. their electronic configuration of valence shell is identical. It organizes elements according to an idealized orbital filling (instead of valence). He was the youngest of fourteen living children. He concluded that there was no correlation between the frequency and the atomic mass.
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