This document defines and compares various periodic properties including atomic radii, ionization energy, electron affinity, ionic radii, valence electrons, and electronegativity. It states that atomic radii decreases left to right and increases down a group. Ionization energy generally increases across a period and decreases down a group. Electron affinity is the energy released or absorbed when an atom gains or loses an electron. Ionic radii are smaller for cations and larger for anions. Valence electrons are those involved in bonding and their number varies by main group element. Electronegativity generally increases across a period and decreases down a group.

1. Chapter 5.3Electron Configurations and Periodic properties

2. Objectives:Define atomic radii and ionic radii, ionization energy, electron affinity, and electronegativity.Compare periodic trends for these properties and state reasons for variations.Define valence electrons, and state how many are present in atoms of each main-group element. Compare the these same properties of d-block elements with those of the main-group elements

3. Atomic RadiiDefined as one-half the distance between the nuclei of identical atoms that are bonded togetherPeriod trendsDecrease from left to rightDue to increasing positive chargeGroup trends

4. Increase down a group

5. Due to occupying higher energy levelsAtomic Radii

6. Ionization EnergyDefined as energy required to remove one electron from a neutral atom of an element (IE)A + energy A+ + e-Ion – atom or group of bonded atoms that has a positive or negative charge.Ionization EnergyPeriod trendsGenerally increase across a periodDue to increasing nuclear chargeGroup trends

7. Generally decrease down a group

8. Due to electron shielding of outer electronsElectron AffinityDefined as the energy change that occurs when an electron is acquired by a neutral atomA +e- A- + energy Quantity released represented by a negative number

9. Forced

10. UnstableA +e- + energyA-Quantity absorbed represented by a positive numberIonic radiiCation – positive ionFormed by loss of one or more electronsSmaller due to removal of electron & stronger pull by nucleus on remaining electronsAnion– negative ion

11. Formed by gain of one or more electrons

12. Larger due to addition of electron & remaining electrons are not pulled as strongly by nucleusIonic Radii