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Chapter 5 The Periodic Table Dimitri Mendeleev Mendeleev’s Proposal Arranged the elements into rows in order of increasing mass. Elements with similar properties were in the same column. Mendeleev ‘s Predictions Mendeleev predicted where new elements would appear in the table. Properties of new elements showed how useful his periodic table could be. Homework 5-1 Worksheet Due: 11/5/08 Periodic Table Arrangement of the elements: Chemical Properties Atomic Number Number of Protons Group Vertical Column Repeating Chemical Properties Increase Mass Group 11-1B Groups Same number of Valence Electrons (Number of Electrons in the Outer Energy Level!!) Be Group 2 Mg Ca Ba Ra Sr Periods Horizontal Rows Same Number of Energy Levels Period - 2 Li Be B C N O F Ne H - Hydrogen C - Carbon O - Oxygen Fe - Iron (ferrum) He - Helium Cu - Copper (cuprum) Hg - Mercury (hydragyrum) Co - Cobalt Unp - Unnilpentium Names and Chemical Symbols Same group - Same number of electrons in their outer shells. Group 1 (H) – 1eGroup 2 (Be) – 2eGroup 13 (B) – 3eGroup 14 (C) – 4eGroup 15 (N) – 5eGroup 16 (O) – 6eGroup 17 (F) – 7eGroup 18 (He) – 8e- Atomic Number (# of Protons) Symbol Average Atomic Mass (31) Name 15 P 30.96376 Phosphorus Atomic Mass Unit Atomic mass unit is equal to one-twelfth of the mass of the nucleus of a carbon-12 atom. Atomic Mass Unit Atomic Mass Unit + p 0 n Proton: Atomic Mass – 1amu Neutron: Atomic Mass – 1amu Atomic Mass of 7 amu Isotopes Atoms of the same element can have different numbers of neutrons . Isotopes of Chlorine 17 Cl 35 17 Cl 37 17 Proton 18 Neutrons 76% 17 Proton 20 Neutrons 24% Average Weighted Mass of Chlorine 35.453amu Metalloids Metals NonMetals Metals 75% of the Elements!!! Metals Physical Properties of Metals: 1. Metallic shine or luster. 2. Usually solids at room temperature. Metals 3. Malleable (Hammered, pounded, or pressed into different shapes without breaking.) Metals 4. Ductile: (Drawn into thin sheets or wires without breaking.) 5. Good conductors of heat and electricity. Metals Metals tend to give up e-. Na Most Reactive Metals Fr Li Francium Most Active Metal Non-Metals There are 17 nonmetals. They have four major physical properties. Non-Metals Physical Properties 1. Rarely have metallic luster. 2. Usually gases at room temperature. Non-Metals 3. Nonmetallic solids are neither malleable nor ductile. 4. Poor conductors of heat and electricity. Non-Metals Non-Metals tend to gain e-. Cl Most Reactive Non-Metal F I Fluorine Most Active Non-Metal The B Si Ge As Sb Te Po Metalloids seven metalloids are: B Si Ge As Sb Te Po Metalloid Properties Characteristics in between that of the metals and the nonmetals. Sometimes they are good conductors of heat and electricity. Variations across a Period Across a Period Less Metallic more Non-Metallic Homework 5-2 Worksheet Due: 11/13/08 Valence Electrons The electrons in the highest occupied energy level of an atom. Valence Electrons Elements in a group have similar properties because they have the same number of valence electrons.. Boron Carbon Nitrogen Oxygen Halogens Noble Gases Alkaline Earth Metals Alkali Metals Li Na K Rb Cs Fr Alkali Metal Group 1A Very reactive metals. Do not occur freely in nature. Only one electron in their outer shell. (1 valence Electron) Most reactive metal!!!! Alkaline Earth Metal Be Group 2A Mg Ca Sr Ba Ra Very reactive Not found free in nature. Two electron in their outer shell. (2 Valence Electron) Magnesium and Calcium important elements in life. B Al Ga In Tl Boron Family Group 3A Three electrons in their outer shell. (3 Valence Electrons) Aluminum is the most abundant metal in the Earth’s crust. Carbon Family C Group 4A. Four electrons in their outer shell. Si (4 Valence Electrons) Ge Consists of: Sn One nonmetal (carbon) Two metals (tin and lead) Two metalloids (silicon and germanium). Pb Except for water, most compounds in your body contain carbon. N P Nitrogen Family Group 5A. Five electrons in the outermost energy level. As (5 Valence Electrons) Sb They physical and chemical properties that are strikingly Bi different. N and P make up fertilizer. O S Se Te Po Oxygen Family Group 6A. Six electrons in their outermost energy level. (6 Valence Electrons) Oxygen is the most abundant element in the earth’s crust. F Cl Br I At Halogens The halogens are five non-metallic elements found in group 7A of the periodic table. All halogens have 7 electrons in their outer shells. The halogens exist, at room temperature, in all three states of matter. Noble Gases He The six noble gases are found in Ne group 8A of the periodic table. These elements were considered to Ar be inert gases. Kr All noble gases have the maximum number of electrons possible in Xe their outer shell (2 for Helium, 8 for all others), making them stable. Rn Colorless/Odorless Gases Electron Dot Diagram Lewis Diagram Dot Diagram: • Symbol of the element • Dots for Valence Electrons. (Outer most energy level Electrons) C Cl Ne Na Homework 5-3: Worksheet Due: 11/14/08 Word-Wise & Math Due: 11/17/08 Test: 11/19/08 Test 11/20/07