Module 7 Day 2
Page 1: Announcements
Exam scores will be posted to Blackboard on Tuesday.
The exam key is posted on Blackboard.
Akindi bubble sheets have been mailed to you.
Page 2: Module 7 Overview
Module Title
Periodic Properties Day 1 2/19
Topics Covered
Introduction to Periodic Properties
Periodic Variations in Element Properties
Variation in Covalent Radius
Variation in Ionic Radii
Upcoming Topics
Day 2 2/24: Variation in Ionization Energies
Variation in Electron Affinities
Page 3: Ionization Energy
Definition: The energy required to remove the most loosely bound electron from a gaseous atom in its ground state.
Equation: X(g) ⟶ X+(g) + e−
First Ionization Energy (IE1) values are always positive, indicating energy is always required to remove electrons from atoms or ions.
Page 4: Trends in Ionization Energies
General Trends
Down a Group: First ionization energy decreases, easier to remove an electron due to increasing atomic size and distance from the nucleus.
Across a Period: First ionization energy generally increases from left to right as effective nuclear charge increases, making it harder to remove an electron.
Page 5: Valence Orbital Diagrams
Example Question: Determine which valence orbital diagram has the greatest first ionization energy among Ca, Ge, Ga, Br.
Key Concept: The closer an atom is to having a full valence shell, the harder it is to remove an electron.
Page 6: First Ionization Energies of Elements
Graph plotting first ionization energy for the first 20 elements against atomic number.
Notable elements:
Group 2 elements (Be, Mg, Ca) show slightly larger IE values than expected.
Group 16 elements (O, S) also show slightly larger IE values than expected.
Page 7: Deviations in Ionization Energy Trend
Key Deviations
Beryllium (Be) vs Boron (B):
Be has a higher IE than B, despite boron's expected trend.
Configurations: Be [He]2s², B [He]2s²2p¹.
Explanation: Removing an s electron from Be is harder than removing a p electron from B, reflecting expected patterns in ionization energies.
Page 8: More Deviations in Trends
Electron Pairing Effects
Removing one electron from O decreases electron-electron repulsion in the 2p orbital, making it more favorable compared to N.
Configurations: N [He]2s²2p³, O [He]2s²2p⁴.
Results in a lower IE than predicted by the trend.
Page 9: Successive Ionization Energies
Definition: Energy required to remove the most loosely bound electron from a gaseous atom (IE1), followed by removal of successive electrons (IE2, IE3, etc.).
General Trend: Ionization energies increase successively.
Example Equations:
IE1: X(g) ⟶ X+(g) + e−
IE2: X+(g) ⟶ X2+(g) + e−
Page 10: Ionization Energies and Charge
Trend: IE1 < IE2 < IE3. Removal of electrons from cations requires more energy due to increased electrostatic attraction.
Note: Removal of electrons becomes more challenging as positive charge increases in cations.
Page 11: Tables of Successive Ionization Energies
Example Elements and Their Ionization Energies
Various elements with their successive IEs outlined in kJ/mol.
Note that large increases in energy correspond to the removal of core electrons indicating they are harder to remove than valence electrons.
Page 12: Core Electrons and Large Increases
For Ga, the transition between IE3 → IE4 shows a significant increase indicative of core electron removal.
Page 13: Prediction of Highest Ionization Energy
Question: Which of the following will have the highest ionization energy? F, Sc2+, Ca2+, Ge3+
Page 14: Ionization Energy Configurations
Breakdown of configurations and predictions for ionization energies based on electron configurations for F, Sc2+, Ca2+, Ge3+.
Page 15: Electron Affinity
Definition: Energy change during the addition of an electron to a gaseous atom.
Reaction Equation: X(g) + e− ⟶ X−(g)
Characteristics: Can be exothermic (releasing energy) or endothermic (absorbing energy).
Page 16: Trends in Electron Affinity
Easier to add electrons as effective nuclear charge increases.
Electron affinities become more negative across a period, generally favoring gaining an electron.
Exceptions: Noble gases exhibit low electron affinity due to complete valence shells.
Page 17: Deviation Trends in Electron Affinity
Group 2 and Group 15 see additional challenges in adding electrons due to electronic configuration and pairing issues.
Page 18: Prediction of Greatest Electron Affinity
Question: Which element would likely have the greatest electron affinity: Li, Ca, S, Br?
Page 19: Comparison of Ionization Energies
Question: Which element is likely to have the largest first ionization energy among Na, H, Li, and Be?
Page 20: Electron Configuration Changes
Configuration: [Og] 8s²7d¹⁰6f¹⁴5g¹⁸p⁵ transforming to [Og] 8s²7d¹⁰6f¹⁴5g¹⁸p⁶ (gain of an electron).
Page 21: Order of Increasing Ionization Energy
Determine the order of increasing ionization energy among Mg, I, Cl based on periodic trends.
Page 22: Electron Configuration Excitation
Configuration change from [Og] 8s²7d¹⁰6f¹⁴5g¹⁸p⁵ to [Og] 8s²7d¹⁰6f¹⁴5g¹⁸p⁴9s¹ indicates excitation of an electron to a higher energy level.
Page 23: Cation Formation
Configuration change from [Og] 8s²7d¹⁰6f¹⁴5g¹⁸p⁵ to [Og] 8s²7d¹⁰6f¹⁴5g¹⁸p⁴ signifies loss of one electron, forming a cation.
Page 24: Quantum Numbers Prediction
Determine possible quantum numbers for the electron removed in the first ionization of Na, based on its electron configuration.