Do Now!!! Write two interesting things you learned in last night’s article. Then turn in your Do Now sheet! L. Bernard, 2015

Organizing and Classifying the Elements on the Periodic Table Chapter 6.1 and 6.2 Organizing and Classifying the Elements on the Periodic Table L. Bernard, 2015

Chapter 6.1 Organizing the Elements L. Bernard, 2015

How are the elements organized on the periodic table? L. Bernard, 2015

Early Organization of Elements On 13 elements identified by the 1700’s Chemists suspected other elements existed Some where even named, but unable to isolate these elements By 1775, 5 new elements were identified Including hydrogen, oxygen, and nitrogen L. Bernard, 2015

Early Organization of Elements Early chemists used properties of elements to sort them into triads Similar reactivity with metals Colorless, odorless gases Not all known elements could be grouped into triads L. Bernard, 2015

Mendeleev’s Periodic Table Russian chemist and teacher, Dmitri Mendeleev In 1869, Mendeleev published the first table of elements Organized elements into groups based on repeating properties Mainly increasing atomic mass L. Bernard, 2015

Mendeleev’s Periodic Table L. Bernard, 2015 Published in 1869; Left blanks for undiscovered elements Organized by increasing atomic mass

Problems with Mendeleev’s Table Created his table before scientists discovered the structure of atoms What property of the atom would make organizing the periodic table by increasing atomic mass problematic??? L. Bernard, 2015

Modern Day Periodic Table Organized by increasing atomic number Periodic Law When elements are arranged by increasing atomic number, there is a periodic repetition of their physical and chemical properties L. Bernard, 2015

Metals, Nonmetals, and Metalloids Three Broad Classes of Elements L. Bernard, 2015

L. Bernard, 2015

Chapter 6.2 Classifying the Elements L. Bernard, 2015

Reading the Periodic Table Columns = Groups or Family 1A = Alkali Metals 2A = Alkaline Earth Metals 7A = Halogens (“salts”) 8A = Noble Gases Rows = Period Based on principle quantum number L. Bernard, 2015

Reading the Periodic Table Halogens Group 7A Very reactive elements Combine with metals to make salts L. Bernard, 2015

Reading the Periodic Table Noble Gases (Inert Gases) Group 8A Rarely take part in reactions, most stable elements L. Bernard, 2015

Reading the Periodic Table Representative Elements Groups 1A-7A Wide range of physical and chemical properties s and p orbitals are not completely filled L. Bernard, 2015

Reading the Periodic Table Transition Elements B group of elements Characterized by the presence of electrons in the d orbital Once known as “rare earth metals” Misleading since not all these elements are rare or from the earth! L. Bernard, 2015

Reading the Periodic Table Inner Transition Elements Characterized by the presence of electrons in the f orbital L. Bernard, 2015

Characteristics of Metals, Non-metals, and Metalloids L. Bernard, 2015

Metals Most elements are metals Good conductors of heat and electricity High luster and sheen (able to reflect light) Solid at room temperature Ductile Malleable L. Bernard, 2015

Non-metals Greater variation of physical properties among these elements Most are gases at room temperature However, a few are solids (sulfur and phosphorus) and one is a liquid (bromine) Poor conductors of heat and electricity Brittle L. Bernard, 2015

B, Si, As, Te, At, Ge, Sb Metalloids Properties of both metals and nonmetals Changing the conditions can change whether a metalloid acts like a metal or a nonmetal Etc: silicon is a poor conductor of electricity; when mixed with boron it will conduct electricity well The 7 metalloids are: B, Si, As, Te, At, Ge, Sb L. Bernard, 2015