1.PERIODIC CLASSIFICATION OF ELEMENTS | DOBEREINER'S LAW NEWLAND'S LAW | class 10 board exams

class 10 and 12 board exams 1.PERIODIC CLASSIFICATION OF ELEMENTS | DOBERENIERS LAW | NEWLANDS LAW | PHYSICAL SCIENCE CLASS 10 In the history of the periodic table, Döbereiner's triads were an early attempt to sort the elements into some logical order by their physical properties. In 1817, a letter reported Johann Wolfgang Döbereiner's observations of the alkaline earths; namely, that strontium had properties that were intermediate to those of calcium and barium. By 1829, Döbereiner had found other groups of three elements (hence "triads") whose physical properties were similarly related. He also noted that some quantifiable properties of elements (e.g. atomic weight and density) in a triad followed a trend whereby the value of the middle element in the triad would be exactly or nearly predicted by taking the arithmetic mean of values for that property of the other two elements. class 10 and 12 board exams class 10 and 12 board exams Law of octaves, in chemistry, the generalization made by the English chemist J.A.R. Newlands in 1865 that, if the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements. The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows periodic trends. The seven rows of the table, called periods, generally have metals on the left and nonmetals on the right. The columns, called groups, contain elements with similar chemical behaviours. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases. Also displayed are four simple rectangular areas or blocks associated with the filling of different atomic orbitals. The elements from atomic numbers 1 (hydrogen) through 118 (oganesson) have been discovered or synthesized, completing seven full rows of the periodic table.The first 94 elements, hydrogen through plutonium, all occur naturally, though some are found only in trace amounts and a few were discovered in nature only after having first been synthesized.Elements 95 to 118 have only been synthesized in laboratories or nuclear reactors. The synthesis of elements having higher atomic numbers is currently being pursued: these elements would begin an eighth row, and theoretical work has been done to suggest possible candidates for this extension. Numerous synthetic radioisotopes of naturally occurring elements have also been produced in laboratories. The organization of the periodic table can be used to derive relationships between the various element properties, and also to predict chemical properties and behaviours of undiscovered or newly synthesized elements. Russian chemist Dmitri Mendeleev published the first recognizable periodic table in 1869, developed mainly to illustrate periodic trends of the then-known elements. He also predicted some properties of unidentified elements that were expected to fill gaps within the table. Most of his forecasts proved to be correct. Mendeleev's idea has been slowly expanded and refined with the discovery or synthesis of further new elements and the development of new theoretical models to explain chemical behaviour. The modern periodic table now provides a useful framework for analyzing chemical reactions, and continues to be widely used in chemistry, nuclear physics and other sciences. Some discussion remains ongoing regarding the placement and categorisation of specific elements, the future extension and limits of the table, and whether there is an optimal form of the table. Feel free to ask any doubts in cooment section like share subscribe share with your friends on class 10 class 10 and 12 board exams class 10 and 12 board exams class 10 and 12 board exams class 10 and 12 board exams periodic table of elements,periodic table of videos,newland's law of octaves,dobereiners triads,dobereiner's triads,periodic classification of elements class 10,moseley's law,moosley law,dmitri mendeleev,mendeleev periodic table,limitations of mendeleev periodic table,periodic classification of elements,newlands law of octaves,newlands law,dobereiner's law of triads,triads law,dobereiner's law of triads in hindi,dobereiner's law of triads in english class 10 and 12 board exams class 10 and 12 board exams class 10 and 12 board exams