1. Periodic Trends
Chapter 14.2

2. What are the Periodic Trends
Periodic Trends - patterns of characteristics of atoms in the Periodic Table
Example: atomic size, ionization energy, electronegativity...

3. Atomic radius in periodic groups (Group Trends)
Atomic size generally increases as you move down a group because electrons are added to higher energy level (atom becomes bigger)

4. Atomic Radius in Period (Periodic Trends)
Atomic size generally decreases from left to right as we progress across a period.
Element gets more protons and electrons, but they add electrons to the same principal energy level. More protons and electrons interact stronger when they are added across a period

5. General Trend-Atomic Radius
Decreasing Atomic Radius
Increasing Atomic Radius

6. Ionization Energy
When an atom gains or loses electrons, it becomes an ion.
The energy required to remove electrons is called ionization energy.
First ionization energy - energy to remove the outermost electron in an atom

7. Ionization Energy Ionization energy decreases as you move down a group
This occurs because the further you move down the group, the larger the atom.
Are negatively charged electrons going to be more or less attracted to a positively charged nucleus the further away they get?
Ionization energy increases as you move left to right across a period
This occurs because the nucleus becomes more positive and the size of the atom decreases
Fluorine really wants an 8th electron.

8. General Trend- Ionization Energy
Increasing Ionization Energy
Decreasing Ionization Energy

9. Size of Ions
Positive ions (cations) are smaller than original/neutral atoms (loss of electrons from outer energy layer therefore atomic size decreases)
Negative ions (anions) are larger than original/neutral atoms due to electron shielding (extra electrons repel each other more therefore, atom becomes larger

10. General Trend- Ionic Size
Decreasing Ionic Size
Increasing Ionic Size

11. Electronegativity
Electronegativity - tendency of atoms to attract electrons
Increasing Electronegativity
Decreasing Electronegativity

12. Summary of Periodic Trends