Atomic Radius

1. Atomic Radius By: Damen, Kyle, Tim, and Henry

2. Definition • The distance from the atomic nucleus to the outermost stable electron orbital in a atom at equilibrium.

3. Group Trend • As you go down a column, the atomic radius increases

4. AP Chem explanation • The underlying electrons require some space, so the electrons of the outer shell must be farther from the nucleus.

5. Periodic Trends • As you moves across a row, the radius decreases.

6. AP Chem explanation • There are more protons and electrons with the same outer energy level causing a greater attraction between the outer shell and the nucleus causing a smaller atomic radius.

7. Units for Atomic Radius • Picometers (1 x 10-12m) • Angstroms (1 x 10-10m) A helium atom, having a radius of 31 picometers

8. Exceptions • On reaching the Groups 1B and 2B elements at the end of the series, the size increases slightly because the d subshell is filled, and the electron-electron repulsions cause the size the increase.

9. Extra Stuff Just Cuz We’re in AP • Positively charged ions have smaller radii than neutral atoms (Stronger relative force from nucleus pulling electrons in and/ or loss of electron shell) • Negatively charged ions have larger radii (electrons repel from each other forcing them out more)

10. Some Pictures For Your Enjoyment

12. FIN