1 / 8

Development of the Periodic Table

Development of the Periodic Table. Johann Doberiener (1829). Arranged elements in groups of three (triads) For example: Cl (mass 35) Br (mass 80) I (mass 127) Note: Average mass of the extreme elements =mass of the middle element. John Newland (1865).

baby
Download Presentation

Development of the Periodic Table

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Development of the Periodic Table

  2. Johann Doberiener (1829) • Arranged elements in groups of three (triads) • For example: Cl (mass 35) Br (mass 80) I (mass 127) Note: Average mass of the extreme elements =mass of the middle element

  3. John Newland (1865) • Arranged elements based on the law of octaves. • Elements were arranged by increasing atomic mass • The chemical properties of the elements repeated every 8th element.

  4. Lothar Meyer (1867) • Father of the Modern Periodic table. • Based on increasing atomic mass • Chemical properties of elements reoccur in a periodic fashion.

  5. Dmitri Mendelyeev (1869)(Russian chemist) • Like Meyer prepared a table based on increasing atomic mass. • Consisted of 17 columns with 63 elements • Widely accepted • Constantly revised as new masses were discovered • Left vacant spots for new elements (Ga, Cd,Ge,Tc, Re, Po) • Certain discrepancies as new masses were found: Ar and K, Co and Ni, Te and I

  6. Henry Mosley (1913) • English scientist used x-rays to determine atomic number (number of protons) • Discovered that the properties of elements were periodic functions of their atomic numbers, • Many of the discrepancies disappeared.

  7. Present arrangement • Based on increasing atomic number • Periodic Law: properties of the elements depend on the structure of the atom and vary with the atomic number in a systematic way • Horizontal rows are called periods (#1-7) Indicates the number of principal energy levels. Note: Lanthanide series part of period 6—long period and Actinide series part of period 7—unfinished period Properties of elements change within a period • Vertical columns are called groups or families (#1-18) Indicates the number of valence electrons. Elements within a group have similar properties. Ex.Na and Li

  8. Element Key

More Related