1. Atomic Radius Ionization Energy Electronegativity
Periodic Trends
Atomic Radius
Ionization Energy
Electronegativity

2. Atomic Radius Distance from the nucleus to the valence shell
Measured in picometers(pm)

3. Period Trend Atoms get smaller as you go across a period
Electrons are added to the same energy level
Due to having more protons, stronger attraction pulls electrons in tighter(more proton pulling power)

4. Group Trend
Radius gets larger due to extra energy levels.

5. Ionization Energy
The energy required to lose one valence electron from an atom in its gas phase.
Important when atoms lose electrons to become positive cations

6. Ions
When an element loses an electron it forms a positively charged ion called cation

7. Ions
When an element gains an electron it forms a negatively charged particle called anion.

8. Period Trend Ionization energy increases across a period
Elements have more protons which increases attraction to their valence electrons

9. Group Trend Ionization energy decreases down a group
Atoms have a new valence shell, so the electrons are farther from the nucleus, decreasing the attraction

10. Practice
Which atom in each pair has the larger atomic radius and Ionization energy?
Li or K
Ca or Ni
Ga or B
O or C
Cl or Br
f) Be or Ba

11. Electronegativity
The ability of an atom to “steal” an electron from another atom.
Important when elements gain electrons to become negative anions

12. Across a period Electronegativity increases across a period
Each element has more protons in their nucleus to attract other electrons stronger

13. Down a Group…. Electronegativity decreases down a group
Extra electron shells make the atoms larger, increasing the distance and decreasing attraction.

15. Practice
1. Which of the following elements has the smallest ionization energy; Sodium, Calcium, Potassium, Magnesium. 2. List the following elements in increasing ionization energy (smallest to largest) Cesium, Bismuth, Oxygen, Beryllium 3. List the following elements in the increasing order of electro negativity Chlorine, Flourine, Carbon, Magnesium