CHAPTER 17: ELEMENTS AND THE PERIODIC TABLE CLASSES OF ELEMENTS Lithium Beryllium Oxygen Neon SodiumMagnesium Sulfur Argon Arrange the drawings in this order on your page DRAW THESE BOHR MODELS Elements can be categorized into three broad groupings: metals, those that are not metals, and those that are somewhere in between. p PHYSICAL SCIENCE Metals Few valence electrons Give metals many of their qualities Most of the left two-thirds of the periodic table pp PHYSICAL SCIENCE Nonmetals Hold electrons tightly Four to eight valence electrons Gives nonmetals many of their qualities Hydrogen and the far-right side of the periodic table p PHYSICAL SCIENCE Metalloids Stairstep line on periodic table Semiconductors p PHYSICAL SCIENCE Neutral elements in the same column of the periodic table have the same number of valence electrons Each column is called a family or group Element Families pp PHYSICAL SCIENCE p PHYSICAL SCIENCE The Alkali Metals (Group 1A) Does not include hydrogen One electron in outermost energy level Easily removed Very reactive pp PHYSICAL SCIENCE The Alkaline-Earth Metals (Group 2A) Two valence electrons Less reactive than alkali metals pp PHYSICAL SCIENCE The Transition Elements (Groups 1B-8B) One or two valence electrons All are metals Few are used in their pure forms alloys pp PHYSICAL SCIENCE The Boron Family (Group 3A) Boron is a metalloid Others are metals Three valence electrons pp PHYSICAL SCIENCE The Carbon Family (Group 4A) Four valence electrons Carbon is a part of almost all organic compounds pp PHYSICAL SCIENCE The Nitrogen Family (Group 5A) Five valence electrons Can form more chemical bonds per atom than any other family pp PHYSICAL SCIENCE The Oxygen Family (Group 6A) Six valence electrons Oxygen can be diatomic (O 2 ) or triatomic (O 3 ) pp PHYSICAL SCIENCE The Halogens (Group 7A) Seven valence electrons Very reactive Exist in pure form only as diatomic molecules Found in many salt compounds pp PHYSICAL SCIENCE The Noble Gases (Group 8A) Complete set of valence electrons Exist in nature as pure monatomic gases Noble: dont join other elements Rare on earth pp PHYSICAL SCIENCE The group number tells the number of valence electrons in neutral atoms of that groups elements Elements in the B subgroups have one or two loosely held valence electrons Inner transition elements typically have two valence electrons pp PHYSICAL SCIENCE The horizontal rows of the periodic table are called periods, or series. Elements in the same period do not have similar properties. p PHYSICAL SCIENCE From left to right across a period: Metallic properties decrease Nonmetallic properties increase Number of electrons in outer level increases Period numbers are listed on the left side of the periodic table p PHYSICAL SCIENCE A period number tells how many energy levels the elements in that period have in their ground state Equals the number of the energy level containing the valence electrons p PHYSICAL SCIENCE Fuel cells convert chemical energy to electrical energy and their only byproduct is steam. So why are they not commonly used today? p PHYSICAL SCIENCE PERIODIC TRENDS Valence electrons Distance from nucleus Arrangement Orbitals Electron dot notation Electron Structure pp PHYSICAL SCIENCE p PHYSICAL SCIENCE p PHYSICAL SCIENCE There are many element properties that can be predicted from the periodic table. How many can you identify? pp PHYSICAL SCIENCE