The Periodic Table Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Groups and Periods On the periodic table Elements are arranged by increasing atomic number and according to similar properties. Groups contain elements with similar properties in vertical columns. Periods are horizontal rows of elements.

Groups and Periods Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Periodic Table Inner Transition Metals

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 for the columns from left to right.

Names of Some Representative Elements Several groups of representative elements are known by common names. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Alkali Metals Group 1A(1), the alkali metals, includes lithium, sodium, and potassium. All have 1 valence electron and form 1+ ions.

Alkaline Earth Metals Include: Beryllium Magnesium Calcium Strontium Barium All are chemically reactive due to their outermost energy level having 2 electrons. Form 2+ ions when reacting with non-metals.

Halogens Group 7A(17) the halogens, includes chlorine, bromine, and iodine. All have 7 valence electrons. Form 1- ions when reacting with metals. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Noble Gases Are chemically unreactive. Include: Helium All, but He, have 8 valence electrons. Mr. Queen’s favorite group! Include: Helium Neon Argon Krypton Xenon Radon

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) magnesium 3) boron C. Group 5A(15), Period 2 1) phosphorus 2) arsenic 3) nitrogen

Solution A. Group 7A(17), Period 4 1) Br B. Group 2A(2), Period 3 2) magnesium C. Group 5A(15), Period 2 3) nitrogen

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 © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Properties of Metals, Nonmetals, and Metalloids 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.

Comparing A Metal, Metalloid, and Nonmetal Table 4.3 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

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 ____

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

Learning Check Match the elements to the description: A. Metals in Group 4A(14) 1) Sn, Pb 2) C, Si 3) C, Si, Ge, Sn B. Nonmetals in Group 5A(15) 1) As, Sb, Bi 2) N, P 3) N, P, As, Sb C. Metalloids in Group 4A(14) 1) C, Si, Ge, 2) Si, Ge 3) Si, Ge, Sn, Pb

Solution Match the elements to the description: A. Metals in Group 4A (14) 1) Sn, Pb B. Nonmetals in Group 5A(15) 2) N, P C. Metalloids in Group 4A(14) 2) Si, Ge

Energy Levels Principal Energy levels Are assigned numbers n = 1, 2, 3, 4 and so on. Increase in energy as n increases. Are like the rungs of a ladder with the lower energy levels nearer the nucleus. n = 4 n = 3 n = 2 n = 1

Electron Capacity of Energy Levels Capacity of Principal Energy Levels 1st: 2 electrons 2nd:8 electrons 3rd: 18 electrons (but stable with 8) 4th: 32 electrons (but stable with 8)

Valence Electrons Valence electrons Determine the chemical properties of the elements. Are the electrons in the highest energy level. Are related to the Group number of the element. Example: Phosphorus has 5 valence electrons 5 valence electrons P Group 5A(15) 2, 8, 5

Groups and Valence Electrons All the elements in a group have the same number of valence electrons. Example: Elements in Group 2A(2) have two (2) valence electrons. Be 2, 2 Mg 2, 8, 2 Ca 2, 8, 8, 2 Sr 2, 8, 18, 8, 2

Periodic Table and Valence Electrons Representative Elements Group Numbers 1 2 13 14 15 16 17 18 H He 1 2 Li Be Al C N O F Ne 2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,8 Li Mg Ge Si P S Cl Ar 2,8,1 2,8,2 2,8,3 2,8,4 2,8,5 2,8,6 2,8,7 2,8,8

Learning Check State the number of valence electrons for each: A. O 1) 4 2) 6 3) 8 B. Al 1) 13 2) 3 3) 1 C. Cl 1) 2 2) 5 3) 7

Solution State the number of valence electrons for each. A. O 2) 6 2) 6 B. Al 2) 3 C. Cl 3) 7

Atomic Size Atomic radius Is the distance from the nucleus to the valence electrons. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Atomic Radius Within A Group Atomic radius increases Going down each group of representative elements. As the number of energy levels with electrons increases. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Atomic Radius Across a Period Atomic radius decreases Going from left to right across a period. As more protons increase effective nuclear attraction for valence electrons. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Learning Check Select the element in each pair with the larger atomic radius. A. Li or K B. K or Br C. P or Cl Solution: A. K B. K C. P