This document discusses the development of the modern periodic table. It describes the early classification systems developed by (a) Dobereiner, who arranged elements into triads based on similar properties; (b) Newlands, who correlated properties with atomic mass; and (c) Lother Meyer, who plotted atomic mass vs. volume and found periodic trends. It then focuses on (d) Mendeleev's periodic table, which arranged elements by atomic mass and predicted new discoveries. The document lists the periods in Mendeleev's table and notes that his table simplified element study and allowed prediction of new elements.
This document discusses the development of the modern periodic table. It describes the early classification systems developed by (a) Dobereiner, who arranged elements into triads based on similar properties; (b) Newlands, who correlated properties with atomic mass; and (c) Lother Meyer, who plotted atomic mass vs. volume and found periodic trends. It then focuses on (d) Mendeleev's periodic table, which arranged elements by atomic mass and predicted new discoveries. The document lists the periods in Mendeleev's table and notes that his table simplified element study and allowed prediction of new elements.
This document discusses the development of the modern periodic table. It describes the early classification systems developed by (a) Dobereiner, who arranged elements into triads based on similar properties; (b) Newlands, who correlated properties with atomic mass; and (c) Lother Meyer, who plotted atomic mass vs. volume and found periodic trends. It then focuses on (d) Mendeleev's periodic table, which arranged elements by atomic mass and predicted new discoveries. The document lists the periods in Mendeleev's table and notes that his table simplified element study and allowed prediction of new elements.
This document discusses the development of the modern periodic table. It describes the early classification systems developed by (a) Dobereiner, who arranged elements into triads based on similar properties; (b) Newlands, who correlated properties with atomic mass; and (c) Lother Meyer, who plotted atomic mass vs. volume and found periodic trends. It then focuses on (d) Mendeleev's periodic table, which arranged elements by atomic mass and predicted new discoveries. The document lists the periods in Mendeleev's table and notes that his table simplified element study and allowed prediction of new elements.
(a) Dobereinerís Triads : He arranged similar elements in the groups of three elements called as triads (b) Newlandís Law of Octave : He was the first to correlate the chemical properties of the elements with their atomic masses. (c) Lother Meyerís Classification : He plotted a graph between atomic masses against their respective atomic volumes for a number of elements. He found the observations ; (i) elements with similar properties occupied similar positions on the curve, (ii) alkali metals having larger atomic volumes occupied the crests, (iii) transitions elements occupied the troughs, (iv) the halogens occupied the ascending portions of the curve before the inert gases and (v) alkaline earth metals occupied the positions at about the mid points of the descending portions of the curve. On the basis of these observations he concluded that the atomic volumes (a physical property) of the elements are the periodic functions of their atomic masses. (d) Mendeleevís Periodic Table : Mendeleevís Periodicís Law the physical and chemical properties of the elements are the periodic functions of their atomic masses.
Periods Number of Elements Called as
st (1) n = 1 2 Very short period (2)nd n = 2 8 Short period rd (3) n = 3 8 Short period th (4) n = 4 18 Long period th (5) n = 5 18 Long period th (6) n = 6 32 Very long period (7)th n = 7 19 Incomplete period
Merits of Mendeleevís Periodic table:
It has simplified and systematised the study of elements and their compounds. It has helped in predicting the discovery of new elements on the basis of the blank spaces given in its periodic table.
