Chapter 5 Electronic Structure And Periodic Trends

Chapter 5 Electronic Structureand Periodic Trends5.3Sublevels and OrbitalsA p sublevel consists of three p orbitals.1Basic ChemistryCopyright 2011 Pearson Education, Inc.

Energy LevelsEnergy levels are assigned quantum numbers n 1, 2, 3, 4,and so on increase in energy as the value of n increases have a maximum number of electrons equal to2n22Basic ChemistryCopyright 2011 Pearson Education, Inc.

SublevelsA sublevel contains electrons with the sameenergy has the same shape but increases involume at higher energy levels is found within each energy level is designated by the letters s, p, d, or f3Basic ChemistryCopyright 2011 Pearson Education, Inc.

Energy of SublevelsIn any energy level the s sublevel has the lowest energy the s sublevel is followed by the p, d, fsublevels higher sublevels are possible, but onlys, p, d, f sublevels are needed to holdthe number of electrons in the atomsknown today4Basic ChemistryCopyright 2011 Pearson Education, Inc.

Number of SublevelsThe number of sublevels in an energy level is the same as the principalquantum number, n.5Basic ChemistryCopyright 2011 Pearson Education, Inc.

OrbitalsAn orbital is a three-dimensional spacearound a nucleus where anelectron is found most of thetime has a shape that representselectron density (not a paththe electron follows) can hold up to two electrons contains two electrons thatspin in opposite directions6Basic ChemistryCopyright 2011 Pearson Education, Inc.

s OrbitalsAn s orbital has a spherical shapearound the nucleus increases in size aroundthe nucleus as the energylevel n value increases is a single orbital found ineach s sublevelAll s orbitals have sphericalshapes that increase in volume athigher energy levels.7Basic ChemistryCopyright 2011 Pearson Education, Inc.

p OrbitalsA p orbital has a two-lobed shape is one of three p orbitals that make up each psublevel, each aligned along a different axis increases in size as the value of n increases8Basic ChemistryCopyright 2011 Pearson Education, Inc.

Sublevels and OrbitalsEach sublevel consists of a specific numberof orbitals. an s sublevel contains one s orbital a p sublevel contains three p orbitals a d sublevel contains five d orbitals an f sublevel contains seven f orbitals9Basic ChemistryCopyright 2011 Pearson Education, Inc.

Electron CapacityThe total number of electrons in all the sublevels adds up to give themaximum number of electrons (2n2) allowed in an energy level.10Basic ChemistryCopyright 2011 Pearson Education, Inc.

Learning CheckIndicate the number and type of orbitals in eachof the following:A. 4s sublevelB. 3d sublevelC. n 311Basic ChemistryCopyright 2011 Pearson Education, Inc.

SolutionIndicate the number and type of orbitals in each ofthe following:A. 4s sublevelone 4s orbitalB. 3d sublevelfive 3d orbitalsC. n 3one 3s orbital, three 3p orbitals,and five 3d orbitals12Basic ChemistryCopyright 2011 Pearson Education, Inc.

Learning CheckThe number ofA. electrons that can occupy a p orbital is1) 12) 23) 3B. p orbitals in the 2p sublevel is1) 12) 23) 3C. d orbitals in the n 4 energy level is1) 12) 33) 5D. electrons that can occupy the 4f sublevel is1) 213Basic Chemistry2) 63) 14Copyright 2011 Pearson Education, Inc.

SolutionThe number ofA. electrons that can occupy a p orbital is2) 2B. p orbitals in the 2p sublevel is3) 3C. d orbitals in the n 4 energy level is3) 5D. electrons that can occupy the 4f sublevel is3) 1414Basic ChemistryCopyright 2011 Pearson Education, Inc.

Chapter 5 Electronic Structureand Periodic Trends5.4Drawing Orbital Diagrams andWriting Electron ConfigurationsIn the orbital diagram of carbon, two electrons occupy the 1s orbital, twoelectrons occupy the 2s orbital, and two electrons each occupy a 2p orbital inthe 2p sublevel.15Basic ChemistryCopyright 2011 Pearson Education, Inc.

Order of FillingEnergy levels fill with electrons in order of increasing energy beginning with quantum number n 1 beginning with s followed by p, d, and f16Basic ChemistryCopyright 2011 Pearson Education, Inc.

Energy Diagram forSublevelsThe orbitals of an atom fill inorder of increasing energy of thesublevels beginning with 1s.17

Orbital DiagramsAn orbital diagram shows orbitals as boxes in each sublevel electrons in orbitals as vertical arrows electrons in the same orbital with oppositespins (up and down vertical arrows)18

Order of FillingElectrons in an atom fill each orbital in a sublevel with oneelectron until half full then pair up with an electron ofopposite spin19

Writing Orbital DiagramsThe orbital diagramfor carbon consists of two electrons in the1s orbital two electrons in the2s orbital one electron each intwo of the 2p orbitals20

Learning CheckWrite the orbital diagrams forA. nitrogenB. oxygenC. magnesium21

SolutionWrite the orbital diagrams for1s2sA. nitrogenB. oxygenC. magnesium222p3s

Electron ConfigurationAn electron configuration lists the sublevels filling with electrons in order ofincreasing energy uses superscripts to show the number of electronsin each sublevel for carbon is as follows:23

Period 1 ConfigurationsIn Period 1, the first two electrons go into the1s orbital.24

Abbreviated ConfigurationsAn abbreviated configuration shows the symbol of the noble gas in brackets thatrepresents completely filled sublevels the remaining electrons in order of their sublevelsExample: Fluorine has a configuration andabbreviated electron configuration ofOrbital DiagramElement25ElectronConfigurationAbbreviated ElectronConfiguration

Period 2 Configurations26

Period 3 Configurations27

Learning CheckA. The correct electron configuration for nitrogen is1) 1s22p52) 1s22s22p63) 1s22s22p3B. The correct electron configuration for oxygen is1) 1s22p62) 1s22s22p43) 1s22s22p6C. The correct electron configuration for calcium is1) 1s22s22p63s23p63d22) 1s22s22p63s23p64s23) 1s22s22p63s23p828

SolutionA. The correct electron configuration for nitrogen is3) 1s22s22p3B. The correct electron configuration for oxygen is2) 1s22s22p4C. The correct electron configuration for calcium2) 1s22s22p63s23p64s229

Learning CheckWrite the electron configuration and abbreviatedconfiguration for each of the following elements:A. ClB. SC. K30

SolutionA. Cl1s22s22p63s23p5[Ne]3s23p5B. S1s22s22p63s23p4[Ne]3s23p4C. K1s22s22p63s23p64s1[Ar]4s131

Chapter 5 Electronic Structureand Periodic Trends5.5Electron Configurations and thePeriodic Table32Basic ChemistryCopyright 2011 Pearson Education, Inc.

Sublevel Blocks on thePeriodic TableThe periodic table consists of sublevel blocksarranged in order of increasing energy. Groups 1A(1)-2A(2) s level Groups 3A(13)-8A(18) p level Groups 3B(3) to 2B(12) d level Lanthanides/Actinides33 f level

Sublevel BlocksElectron configurations follow the order of sublevels onthe periodic table.34

Using Sublevel BlocksTo write an electronconfiguration usingSublevel blocks, locate the element onthe periodic table starting with H in1s,write each sublevelblock in order goingfrom left to right acrosseach period write the number ofelectrons in each block35

Writing ElectronConfigurationsUsing the periodic table, write the electronconfiguration for silicon.SolutionPeriod 1Period 2Period 31s block2s 2p blocks3s 3p blocks1s22s2 2p63s23p2 (Si)Writing all the sublevel blocks in order gives1s22s22p63s23p236

Electron Configurations dSublevel The 4s orbital has a lower energy that the 3d orbitals. In potassium, K, the last electron enters the 4s orbital,not the 3d (as shown below).1s2s 2p3s 3p 3dAr1s22s2 2p63s2 3p6K1s22s2 2p63s2 3p64s1Ca1s22s2 2p63s2 3p64s2Sc1s22s2 2p63s2 3p6 3d14s2Ti1s22s2 2p63s2 3p6 3d24s2374s

Writing ElectronConfigurationsUsing the periodic table, write the electronconfiguration for manganese.SolutionPeriod 1Period 2Period 3Period 41s block2s 2p blocks3s 3p blocks4s 3d blocks1s22s2 2p63s2 3p64s2 3d5 (at Mn)Writing all the sublevel blocks in order gives1s2 2s2 2p63s2 3p6 4s2 3d538

Writing ElectronConfigurationsUsing the periodic table, write the electronconfiguration for iodine.SolutionPeriod 1Period 2Period 3Period 4Period 51s block2s 2p blocks3s 3p blocks4s 3d 3p blocks5s 4d 5p blocks1s22s23s24s25s2Writing all the sublevel blocks in order gives1s2 2s2 2p63s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5(iodine)392p63p63d10 4p64d10 5p5

4s Block40

3d Block41

4p Block42

Learning CheckA. The last two sublevel blocks in the electronconfiguration for Co are1) 3p64s22) 4s24d73) 4s23d7B. The last three sublevel blocks in the electronconfiguration for Sn are1) 5s25p24d102) 5s24d105p23) 5s25d105p243

SolutionsA. The last two sublevel blocks in the electronconfiguration for Co are3) 4s23d7B. The last three sublevel blocks in the electronconfiguration for Sn are2) 5s24d105p244

Learning CheckUsing the periodic table, write the electronconfiguration and abbreviated configuration foreach of the following elements:A. ZnB. SrC. I45

SolutionA. Zn1s22s22p63s23p64s23d10[Ar] 4s23d10B. Sr1s22s22p63s23p64s23d104p65s2[Kr]5s2C. 46

Learning CheckGive the symbol of the element that hasA. [Ar]4s23d6B. Four 3p electronsC. Two electrons in the 4d sublevelD. Electron configuration1s22s22p63s23p64s23d247

SolutionGive the symbol of the element that hasA. [Ar]4s23d6FeB. Four 3p electronsSC. Two electrons in the 4d sublevelZrD. Electron configuration1s22s22p63s23p64s23d2Ti48

Chapter 5 ElectronConfiguration and PeriodicTrends5.6Periodic Trends of the Elements49Basic ChemistryCopyright 2011 Pearson Education, Inc.

Valence ElectronsThe valence electrons determine the chemical properties of an element are the electrons in the s and p sublevels in thehighest energy level are related to the group number of the elementExample: Phosphorus has 5 valence electrons5 valence electronsP Group 5A(15)501s22s22p6 3s23p3

Group Number and ValenceElectronsAll the elements in a group have the same numberof valence electrons.Example:Elements in Group 2A (2) have two (2) valenceelectrons.Be1s2 2s2Mg1s2 2s2 2p6 3s2Ca1s2 2s2 2p6 3s2 3p6 4s2Sr1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s251

Periodic Table and ValenceElectrons52

Learning CheckState the number of valence electrons for each:A. O1) 42) 63) 8B. Al1) 132) 33) 12) 53) 7C. Cl1) 253

SolutionState the number of valence electrons for each.A. O2) 6B. Al2) 3C. Cl3) 754

Learning CheckState the number of valence electrons for each.A. Calcium1) 12) 23) 3B. Group 6A (16)1) 22) 43) 6C. Tin1) 22) 43) 1455

SolutionState the number of valence electrons for each.A. Calcium2) 2B. Group 6A (16)3) 6C. Tin2) 456

Learning CheckState the number of valence electrons for each.A. 1s22s22p63s23p3B. 1s22s22p63s23p64s23d104p4C. 1s22s22p557

SolutionState the number of valence electrons for each.A. 1s22s22p63s23p35B. 1s22s22p63s23p64s23d104p46C. 1s22s22p5758

Electron-Dot SymbolsAn electron-dot symbol indicates the valence electronsas dots around the symbol ofthe element for Mg shows two valenceelectrons placed as single dotson the sides of the symbol Mg.·Mg · or Mg · or · Mg or · Mg ·59

Writing Electron-Dot SymbolsThe electron-dot symbols for Groups 1A (1) to 4A (14) use single dots·Na ·· Mg ··· Al ···C· Groups 5A (15) to 7A (17) use pairs andsingle dots···P··60··:O··

Groups and Electron-DotSymbols In a group, all the electron-dot symbols havethe same number of valence electrons (dots).Example: Atoms of elements in Group 2A (2)each have two valence electrons.2A (2)· Be ·· Mg ·· Ca ·· Sr ·· Ba ·61

Periodic Table and ElectronDot Symbols62

Learning Check A.X is the electron-dot symbol for1) Na2) K3) Al B. X 1) B63is the electron-dot symbol of2) N3) P

Solution A.X is the electron-dot symbol for1) Na2) K B. X is the electron-dot symbol of2) N643) P

Atomic RadiusThe atomic radius is the distance from the nucleus to the valenceelectrons65

Atomic Radius within a GroupThe atomic radiusincreases going down eachgroup ofrepresentativeelements as the number ofenergy levelsincreases66

Atomic Radius across a PeriodThe atomic radius decreases going from left to right across a period as more protons increase the nuclearattraction for valence electrons67

Learning CheckSelect the element in each pair with the largeratomic radius.A.B.C.68Li or KK or BrP or Cl