CG6+Evolution+of+the+Periodic+Table

Answer the questions, in complete sentences based on the article from Scientific American "The Evolution of the Periodic System".

1.) For each scientist listed, describe the contribution to the development of the periodic table. Antoine Lavoisier - put the first list of elements together; found and termed both oxygen and hydrogen Johann Dobereiner - discovered trends in certain properties of selected groups of elements. Peter Kremers- suggested that certain elements could belong to two triads placed perpendicularly. he broke new ground by comparing elements in two directions. Jean-Baptist-Andre Dumas - focused on devising a set of mathematical equations that could count for the increase in atomic weight among several groups of chemically similar elements. Alexandre Emile Beguyer de Chancourtois - was the first the arrange the chemical elements in order of atomic mass John Newlands - invented the periodic table Julius Meyer - liked to study gases, and continued to pursue a life of research and teaching and wrote another periodic table and corrected the atomic weights of some already known elements. Henry Mosely - he found proof that there is in the atom a fundamental quantity, which increases by regular steps as we pass from one element to the next.

2.) What properties did Mendeleev use to arrange his periodic table? Mendeleev used a system that illustrated a periodicity, or repetition, in the properties of certain elements at certain regular intervals. But what properties did he use? - Ms. H. 3.) What were some of the problems with Mendeleev's table? What discoveries support Mendeleev's Table? Mendeleev assembled his own periodic table. Mendeleev had sufficient confidence in his periodic table to use it to predict several new elements and the properties of their compounds. he also corrected the atomic weights of some already known elements. The problems were that there were only 63 elements and not 109. They also weren't arranged the same way. He was able to work out the atomic mass of the missing elements and the gaps, and their predicted properties and when they were discovered he was right. 4.) On which properties is the modern periodic table arranged? By atomic numbers, mass numbers and different types of elements. 5.) Why is it called the __Periodic__ Table of the Elements? Because it illustrates the repitiion or periodicity in the properties of the elements at certain regular intervals.

Good job! - Ms. H.