1. Periodic Trends/Patterns
CH. 2

2. Periodic Trend Nuclear charge atomic size or radius ionization energy
electron affinity
electronegativity
metallic character
Reactivity
bonding characteristics
crystal configurations
acidic properties
densities

3. Quantum Mechanical Model
Effective Nuclear Charge: The s, p, d, and f orbitals within a given shell have slightly different energies.
The difference in energies between subshells result in electron–electron repulsion which shields outer electrons from the nucleus.
The net nuclear charge felt by an electron is called the effective nuclear charge ( Zeff ).
Zeff

4. Quantum Mechanical Model
Zeff is lower than actual nuclear charge.
Zeff increases toward nucleus ns > np > nd > nf
This explains certain periodic changes observed.

5. Z*
The effective nuclear charge in the actual charge from the nucleus that an electron feels due to attractive forces from the nucleus but also repulsive forces from the other electrons, mainly the core electrons.

6. Atomic radii

7. The Periodic Table 02

8. Periodic Properties 02
Atomic Radii 02:

9. Ions and Ionic Radii 02
Chapter 06

12. Ions and Ionic Radii

14. Trend of ionic radii
The cation of an atom decreases in size while the anion of an atom increases in size.
The trend can not be made according to the periodic table, but by the isoelectronic series.
The more positive an ion is the smaller it is because Zeff increases, while the more negative an ion, the larger it is because Zeff decreases.

15. Ionization Energy
Defined as the amount of energy necessary to remove the outermost electron from an isolated neutral atom in the gaseous state to infinity.
Abbreviation is Ei, it has units of kJ/mol. IE

16. successive ionization energy

17. Ionization Energy
Minor irregularities in the Ei values are explained by looking at the electron configurations.
IE Trend

18. Ionization Energy
Ionization energies vary periodically, which is explained by the changes in Zeff .
Zeff

19. Electron Affinity 01
Electron Energy: Energy change that occurs when an electron is added to an isolated atom in the gaseous state.
Abbreviation is Eea, it has units of kJ/mol. Values are generally negative because energy is released.
Value of Eea results from interplay of nucleus electron attraction, and electron–electron repulsion. EA

20. Electron Affinity 02
EA Trend

21. Periodic properties REACTIVITY - Li

22. Periodic properties - Na

23. Periodic properties - K

24. Metallic Character
The metallic character of atoms can be related to the desire to loose electrons
On the periodic table, the metallic character of the atoms increase down a family and decreases from left to right across a period.

25. Periodic Trend Activities
WebElements
Periodicity and Properties of Elements and Compounds: An Internet Study
Periodic Trends Lesson
Periodic Table Exercises
Our Favorite Element
Structured Curriculum Lesson Plans