Ch3.4 Introduction to the Periodic Table Organization of the Elements

Mendeleev: Father of the Periodic Table Mendeleev is best known for his work on the periodic table; arranging the 63 known elements into a Periodic Table based on atomic mass, which he published in Principles of Chemistry in 1869 Mendeleev provided for variance from strict atomic weight order, left space for new elements, and predicted three yet-to-be-discovered elements including eke-silicon and eke-boron. His table did not include any of the Noble Gases, however, which had not yet been discovered.

Metals, Nonmetals, Metalloids The periodic table is further divided into two broad categories of metals and nonmetals. Metals make up a majority of the table. Between the dividing line there is a class of elements that have properties of both metals and nonmetals. These elements are referred to as metalloids. Non metals: halogens, noble gases, H, C, N, O, P, S, Se Metalloids: B Si, Ge, As, Sb, Te, *(At) Metals: The remainder of the elements Actinides: all of the elements following actinium Lanthanides: all of the elements following lanthanum

Organization of the Periodic Table Horizontal rows in the table are referred to as Periods. Hydrogen is period 1, Lithium is period 2, etc. Vertical columns in the table are Groups or Families. Group 1 is called alkali metals, except H Group 2 is called alkaline earth metals Group 17 are called halogens Group 18 are called noble gases Groups 1,2,13-18 are called main group elements Groups 3-12 are called transition metals