Chapter 7 Periodic Properties of the Elements Prepare for Recitation September 15th ALEKS Objective 3 due September 13th ANGEL Quiz 3 September 15th Lecture 7 September 7th Lecture 8 September 9th Lecture 9 September 12th You are advised to read ahead for all three lectures and see the BIG PICTURE FIRST Read Ch 2 5 2 8 Ch 7 1 7 6 Ch 8 1 8 4 Additional Preparation Packet 2 4 5 BLB 6 70 71c 74 75 Packet 6 10 14 BLB 7 11 31 41 48acd 53 94 Packet 7 1 12 BLB 8 22 25 Packet 8 1 2 ALEKS work is necessary but not sufficient for exam level preparation Do not neglect the packet CH110 FA11 SAS 1 Chapter 7 Periodic Properties of the Elements KEY QUESTIONS THE BIG PICTURE How does the periodic table reflect the electronic structure of atoms How do I know what ions an atom might form Remember structure affects function How does an atoms family help me to predict its chemistry What does the periodic table have to do with ionic bonding By the end of Today s Lecture you should know Screening Effects Periodic Properties atomic and ion sizes Isoelectronic series Electron configurations of ions Ionization energies Electron affinities well this is Friday CH110 FA11 SAS 2 Reality Check Exam 1 When and where is Exam 1 What do I bring to Exam 1 Pencils Student ID Calculator Absolutely NO text programmable calculators or wireless devices yes this includes your i Phone We will check Note We will provide the data sheet and periodic table exactly as they appear in your course packet CH110 FA11 SAS 3 Basis for Periodic Properties Electron configurations determine organization of the periodic table properties are periodic and categorize Elemental properties which are determined by size and shape of orbitals atomic number Chemists examine periodic properties experimentally by measuring Atomic sizes Ionization energies Electron affinities Reactivity CH110 FA11 SAS 4 Groups and Periods Properties repeat periodically What electrons control the chemistry of the elements Why do groups have similar properties Some groups to remember the names of CH110 FA11 SAS 5 Atomic Size Observation WHY as n increases orbital increases as n increases orbitals energy becomes Observation WHY number of increases added valence electrons shield ineffectively CH110 FA11 SAS 6 Which is the largest element in the periodic table Two simple rules to usually be right 1 Look at n which determines the 2 For a given n look at CH110 FA11 SAS 7 Effective Nuclear Charge Case study 11Na What is Zeff felt by valence e Zeff The more e the harder it is for the valence eto see the nucleus due to Left to right across a period Zeff CH110 FA11 SAS 8 Practice Problem In which subshell does an electron experience the greatest effective nuclear charge in a many electron atom A 3f B 3p C 3d D 3s E 4s CH110 FA11 SAS 9 Electron Configurations of Ions How do elements form ions Observation Main group atoms tend to form ions with filled e Na Cl 1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s23p5 core electrons valence electrons Na Cl 1s2 2s2 2p6 1s2 2s2 2p6 3s23p6 complete octets Do core electrons participate in chemistry of reactions CH110 FA11 SAS 10 Ionic Size cations are than parent atoms Na 0 97 Na 1 54 anions are than parent atoms Cl 1 81 Cl 0 99 CH110 FA11 SAS 11 Ion Channels Size Matters Voltage gated potassium channels must selectively allow K ions through the cell membrane while preventing Na or Ca2 from passing through They accomplish this by detecting the difference in size between the ions CH110 FA11 SAS 12 Ionization Energy Definition M g M g eM g M 2 g e I1 First ionization energy I2 Second ionization energy electrons are more easily removed because electrons further from the nucleus are stable EXAMPLE Mg 1st I E 735 kJ mol 2nd I E 1445 kJ mol 3rd I E 7730 kJ mol CH110 FA11 SAS 13 Periodic Trends in First Ionization Energy Quantitative look at group 1A Li Na K Rb Cs I1 kJ mol 520 I E 496 size 419 403 376 CH110 FA11 SAS 14 Periodic Trends in First Ionization Energy Ionization going across a period 1st I E kJ mol Na 490 Mg 735 Al Si P S Cl Ar 580 780 1060 1005 1225 1550 CH110 FA11 SAS 15 Exceptions to the Trend It requires energy to remove electrons from atoms It is much harder requires more energy to remove electrons from 1 2 CH110 FA11 SAS 16 Transition Metals s electrons are part of the valence electrons but are lost during ionization will lose d electrons valence s eare gone transition metal ions can have charges EXAMPLES Fe Ar 4s23d6 Fe2 Fe3 Ag Kr 5s14d10 Ag Cu Ar 4s13d10 Cu Cu2 CH110 FA11 SAS 17 Practice Problem Below are successive ionization energies of an atom Which atom is it I1 578 kJ mol I2 1820 kJ mol I3 2750 kJ mol I4 11 600 kJ mol A B C D E S Li Mg Ne Al CH110 FA11 SAS 18 What You Should Know By the end of Friday s Class Periodicity of Atomic Size How does size vary going down a group in the periodic table and why look at n and radius How does size vary going across the periodic table and why look at Zeff and shielding What is effective nuclear charge What affects this Which atoms orbitals experience it more Compare sizes of cations to parent ions Compare sizes of anions to parent ions Know how the size of isolectronic series are affected by shielding CH110 FA11 SAS 19 What You Should Know By the end of Friday s Class Ionization Energy What is the definition What is the sign of ionization energy Why Know how IE varies going down a family and across the periodic table Electron Affinity What is the definition Which groups of elements have a negative EA and why Which groups of elements have a positive EA and why CH110 FA11 SAS 20 What You Should Know By the end of Friday s Class Metal Reactivity How does metal reactivity vary going down a group in the periodic table Why is metal reactivity related to IE How is reactivity related to size Which metal is most reactive How did we demonstrate this in class Halogen Reactivity How does reactivity vary going down the group Why is this order different than for metals How is halogen reactivity related to electron affinity CH110 FA11 SAS 21
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