148x Filetype PDF File size 0.78 MB Source: www.sisd.net
THE PERIODIC TABLE Objective: Explain the use of chemical and physical properties in the historical development of the Periodic Table. ■ Antoine Lavoisier: In the 1700’s complied a list of all know elements (33) organized into 4 categories. – Gases (light, heat, inflammable air, etc.) – Metals (antimony, silver, arsenic, bismuth, zinc, etc.) – Nonmetals (sulfur, phosphorus, pure charcoal, etc.) – Earths (chalk, clay, siliceous earth, etc.) ■ John Newlands: In 1864 he noticed that when the elements were arrange in order of increasing ATOMIC MASS that the properties REPEATED EVERY 8 ELEMENTS. – This pattern is called PERIODIC. – Called this the Law of Octaves. – Not accepted because did not work for all elements and “octave” sounded “unscientific.” Dmitri Mendeleev: 1869 Father of The Periodic Table ■ Also noticed that when the elements were arranged by atomic mass that there was a Periodic Pattern in their properties. ■ His table had vertical rows and horizontal columns. ■ The Columns had SIMILAR PROPERTIES. ■ Left BLANK SPACES for undiscovered elements. ■ Predicted the properties for: – scandium – gallium – germanium ■ LotharMeyers demonstrated the same connection but Mendeleev was FIRST. Henry Moseley (1887 – 1915) ■ MODERN PERIODIC TABLE ■ Problems with Mendeleev’s table: – As new elements were discovered did not fit ■ Vertical Columns: – Groups or Families pattern. – 18 groups ■ Henry Moseley discovered that each element had a ■ Horizontal Rows: UNIQUE NUMBER OF PROTONS. – Periods – 7 periods ■ This is the ATOMIC NUMBER. ■ Representative Elements: – groups 1, 2, 13-18 ■ In 1913 he proposed that the Period Table be ■ Transition Elements: organized by Atomic Number which gave a CLEAR – groups 3-12 Period Pattern. – Inner Transition Metals ■ PERIODIC LAW: There is a periodic repetition of ■ Also classified as: – metals chemical and physical properties of the elements – nonmetals when they arranged by increasing ATOMIC NUMBER. – metalloids
no reviews yet
Please Login to review.