History of the periodic table

Introduction

Hello class,

    We are going to talk adout the history of thr periodic table and the arrangement.

Task

Create a WedQuest for the history and arrangement of the Periodic Table.

Process

The periodic table is an arrangement of the chemical elements, organized on the basis of their atomic numbers, electron configurations and recurring chemical properties. Elements are presented in order of increasing atomic number. The standard form of the table consists of a grid of elements, with rows called periods and columns called groups.

The history of the periodic table reflects over a century of growth in the understanding of chemical properties. The most important event in its history occurred in 1869, when the table was published by Dmitri Mendeleev, who built upon earlier discoveries by scientists such as Antoine-Laurent de Lavoisier and John Newlands, but who is nevertheless generally given sole credit for its development.

 

In 1817, Johann Wolfgang Döbereiner began to formulate one of the earliest attempts to classify the elements. In 1829, he found that he could form some of the elements into groups of three, with the members of each group having related properties. He termed these groups triads. Some of the triads that were classified by Döbereiner are:

  1. chlorine, bromine, and iodine
  2. calcium, strontium, and barium
  3. sulfur, selenium, and tellurium
  4. lithium, sodium, and potassium

In all of the triads, the atomic weight of the middle element was almost exactly the average of the atomic weights of the other two elements.With the elements arranged in a spiral on a cylinder by order of increasing atomic weight, de Chancourtois saw that elements with similar properties lined up vertically.

 

  • The elements, if arranged according to their atomic mass, exhibit an apparent periodicity of properties.
  • Elements which are similar as regards to their chemical properties have atomic weights which are either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly (e.g., K, Rb, Cs).
  • The arrangement of the elements, or of groups of elements in the order of their atomic masses, corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical properties; as is apparent among other series in that of Li, Be, B, C, N, O, and F.
  • The elements which are the most widely diffused have small atomic weights.
  • The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body.
  • We must expect the discovery of many yet unknown elements – for example, elements analogous to aluminium and silicon – whose atomic weight would be between 65 and 75.
  • The atomic weight of an element may sometimes be amended by a knowledge of those of its contiguous elements. Thus the atomic weight of tellurium must lie between 123 and 126, and cannot be 128.
  • Certain characteristic properties of elements can be foretold from their atomic masses.

 

  • It enabled Mendeleev to predict the discovery of new elements and left spaces for them, namely eka-silicon (germanium), eka-aluminium (gallium), and eka-boron (scandium). Thus, there was no disturbance in the periodic table.
  • It could be used by Mendeleev to point out that some of the atomic weights being used at the time were incorrert.
  • It provided for variance from atomic weight order. 

Seaborg's actinide concept of heavy element electronic structure, predicting that the actinides form a transition series analogous to the rare earth series of lanthanide elements, is now well accepted and included in the periodic table. The actinide series is the second row of the f-block (5f series). In both the actinide and lanthanide series, an inner electron shell is being filled. The actinide series comprises the elements from actinium to lawrencium. Seaborg's subsequent elaborations of the actinide concept theorized a series of superheavy elements in a transactinide series comprising elements from 104 to 121 and a superactinide series of elements from 122 to 153.

                              

Conclusion

So in conclusion that is more then enought facts and the periodic table and how and why it is arranged.

Credits

Chelsie Smith 8B

Jaleah Mack 8B

Diamond Rose 8B

Teacher Page

Mrs.Buffington Social Studies and Science teacher