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