2.7 An Introduction to the Periodic Table Periodic Table Dmitri Mendeleev (1834-1907) Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © Houghton Mifflin Company. All rights reserved. 2–2 Groups and Periods On the periodic table, • elements are arranged according to similar properties. • groups contain elements with similar properties in vertical columns. • periods are horizontal rows of elements. Copyright © Houghton Mifflin Company. All rights reserved. 2–3 Groups and Periods Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © Houghton Mifflin Company. All rights reserved. 2–4 Group Numbers Group Numbers • use the letter A for the representative elements (1A to 8A) and the letter B for the transition elements. • also use numbers 1-18 to the columns from left to right. Copyright © Houghton Mifflin Company. All rights reserved. 2–5 Names of Some Representative Elements Several groups of representative elements are known by common names. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © Houghton Mifflin Company. All rights reserved. 2–6 Alkali Metals Group 1A(1), the alkali metals, includes lithium, sodium, and potassium. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © Houghton Mifflin Company. All rights reserved. 2–7 Halogens Group 7A(17) the halogens, includes chlorine, bromine, and iodine. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © Houghton Mifflin Company. All rights reserved. 2–8 Learning Check Identify the element described by the following. A. Group 7A(17), Period 4 1) Br 2) Cl 3) Mn B. Group 2A(2), Period 3 1) beryllium 2) boron 3) magnesium C. Group 5A(15), Period 2 1) phosphorus 2) arsenic 3) nitrogen Copyright © Houghton Mifflin Company. All rights reserved. 2–9 Solution A. Group 7A (17), Period 4 1) Br B. Group 2A (2), Period 3 3) magnesium C. Group 5A(15), Period 2 3) nitrogen Copyright © Houghton Mifflin Company. All rights reserved. 2–10 Metals, Nonmetals, and Metalloids The heavy zigzag line separates metals and nonmetals. • Metals are located to the left. • Nonmetals are located to the right. • Metalloids are located along the heavy zigzag line between the metals and nonmetals. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © Houghton Mifflin Company. All rights reserved. 2–11 Properties of Metals, Nonmetals, and Metalloids Metals • are shiny and ductile. • are good conductors of heat and electricity. Nonmetals • are dull, brittle, and poor conductors. • are good insulators. Metalloids • are better conductors than nonmetals, but not as good as metals. • are used as semiconductors and insulators. Copyright © Houghton Mifflin Company. All rights reserved. 2–12 Comparing a Metal, Metalloid, and Nonmetal Copyright © Houghton Mifflin Company. All rights reserved. 2–13 Learning Check Identify each of the following elements as 1) metal 2) nonmetal 3) metalloid A. sodium ____ B. chlorine ____ C. silicon ____ D. iron ____ E. carbon ____ Copyright © Houghton Mifflin Company. All rights reserved. 2–14 Solution Identify each of the following elements as 1) metal 2) nonmetal 3) metalloid A. sodium 1 metal B. chlorine 2 nonmetal C. silicon 3 metalloid D. iron 1 metal E. carbon 2 nonmetal Copyright © Houghton Mifflin Company. All rights reserved. 2–15 Metals Tend to Lose Electrons Copyright © Houghton Mifflin Company. All rights reserved. 2–16 Nonmetals Tend to Gain Electrons Copyright © Houghton Mifflin Company. All rights reserved. 2–17.