### Summary

Presented in this lesson were several fundamental and important concepts—namely, atomic structure, electron configurations in atoms and the periodic table, and the various types of inter-atomic bonds that hold together the atoms that compose a solid. The various types of atomic bonding, which are determined by the electron structures of the individual atoms, along with geometric atomic arrangements can determine some of the important properties of solid materials. Later in the course, we will move to the next level of the structure of materials, specifically, to some of the geometric atomic arrangements that may be assumed by atoms in the solid state.

### Reminder - Complete all of the Lesson 3 tasks!

You have reached the end of Lesson 3! Double-check the to-do list on the Lesson 3 *Overview* page to make sure you have completed all of the activities listed there before you begin Lesson 4.