1. Periodic Trends
Main Concept:
- Many properties of atoms exhibit periodic trends that are reflective of the periodicity of electronic structure.

2. Influences on Periodic Trends1. 2. 3.
Trends
Ionization Energy
Atomic/Ionic Radii
Electronegativity
Ionic Charges
How does each trend change across the periodic table? Why?
Periodicity and its Implications

3. Periodic Trends
- structure of the periodic table is based on electron configuration patterns and presence of shells (and subshells)
- electron configuration can be deduced from element’s position in periodic table (with some exceptions)

5. Periodic Trends
- For many atomic properties, periodic trends below (and relative values for different atoms and ions) can be understood and explained using Coulomb’s law*, the shell model*, and the concept of shielding/effective nuclear charge*.
First ionization energy
Atomic and ionic radii
Electronegativity
Typical ionic charges
- *Note: This is what you need to draw upon to explain anything on the periodic table

6. - First ionization energy: how much energy is needed to pull off the first valence electron
- Atomic radii: the size of an atom
- Ionic radii: the size of an atom once it has given up or gained electrons
- Electronegativity: the ability of an atom to pull electrons towards itself while bonded
- Typical Ionic Charges: metals give up electrons making them slightly positive; nonmetals will take electrons making them slightly negative

9. Question:
Why would anions be larger than their parent atom?

11. - Periodicity = useful tool when designing new molecules or materials
- replacing an element of one group with another of the same group may lead to a new substance with similar properties.  
ex: if SiO2 can be ceramic, SnO2 may be also

12. Question:
Why would elements in the same group have similar properties? Why might those same elements have slightly different properties?
Based on electron configurations, why would groups 1 and 2 be most likely to give up electrons while group 16 and 17 be most likely to take electrons while group 18 would do neither?