I. History of the Periodic Table Mendeleev Mosely Periodic Law Ch. 5 - The Periodic Table I. History of the Periodic Table Mendeleev Mosely Periodic Law

A. Dmitri Mendeleev Dmitri Mendeleev (1869, Russian) Organized elements by increasing atomic mass. Predicted the existence of undiscovered elements.

B. Henry Mosely Henry Mosely (1913, British) Organized elements by increasing atomic number. Fixed problems in Mendeleev’s arrangement.

C. Periodic Law Properties of elements repeat in a predictable way when atomic numbers are used to arrange elements into groups.

Key Concept How is the modern periodic table organized? In the modern periodic table, elements are arranged by increasing number of protons.

II. Organization Metallic Character Rows & Columns Table Sections Ch. 5 - The Periodic Table II. Organization Metallic Character Rows & Columns Table Sections

A. Metallic Character Metals Nonmetals Metalloids

A. Metallic Character The majority of the elements on the periodic table are classified as metals. Metals are elements that are good conductors of electric current and heat. Except for mercury, metals are solid at room temperature. Most metals are solids. Many metals are ductile; that is, they can be bent.

A. Metallic Character Nonmetals generally have properties opposite to those of metals. Nonmetals are elements that are poor conductors of heat and electric current. Nonmetals have low boiling points – many nonmetals are gases at room temperature. Nonmetals that are solids at room temperature tend to be brittle. If they are hit with a hammer, they shatter or crumble.

A. Metallic Character Metalloid elements are located on the periodic table between metals and nonmetals. Metalloids are elements with properties that fall between those of metals and nonmetals. For example, a metalloid’s ability to conduct electric current varies with temperature. Silicon (Si) and Germanium (Ge) are good insulators at low temperatures and good conductors at high temperatures.

B. Rows and Columns Representative Elements Transition Metals

B. Rows and Columns Group (Family) Period

B. Rows and Columns Each column in the periodic table is called a Group or Family. The elements in a group have the same number of valence electrons, so members of the same group in the periodic table have similar chemical properties. This pattern of repeating properties is the periodic law.

B. Rows and Columns Each column in the periodic table of elements is a Group. Elements in group 1 have _1_ valence electron. Elements in group 2 have _2_ valence electrons. Elements in group 13 have _3_ valence electrons. Elements in group 14 have _4_ valence electrons. Elements in group 15 have _5_ valence electrons. Elements in group 16 have _6_ valence electrons. Elements in group 17 have _7_ valence electrons. Elements in group 18 have _8_ valence electrons.

B. Rows and Columns Each row in the table of elements is a Period. Elements in period _1_ have one energy level. Elements in period _2_ have two energy levels. Elements in period _3_ have three energy levels. Elements in period _4_ have four energy levels. Elements in period _5_ have five energy levels. Elements in period _6_ have six energy levels. Elements in period _7_ have seven energy levels. Horizontally Into Periods

III. Periodic Trends Terms Dot Diagrams The Periodic Table III. Periodic Trends Terms Dot Diagrams

Review There are four pieces of information for each element. 1. _______________ 2. _______________ 3. _______________ 4. ______________

A. Terms Periodic Law Properties of elements repeat periodically when the elements are arranged by increasing atomic number.

A. Terms Valence Electrons e- in the outermost energy level

A. Terms Group # = # of valence e- (except He) Families have similar chemical characteristics. Period # = # of energy levels 1A 2A 3A 4A 5A 6A 7A 8A

B. Dot Diagrams Dots represent the valence e-. Ex.: Sodium Ex.: Chlorine