### How can the crystalline characteristics of metals be modeled through Lego bricks?

The amount of different Lego pieces in the entire world seems almost infinite. But imagine if there were only two types of Lego pieces: the 2 × 2 brick and the 2 × 3 brick.

If the above scenario were true, Legos could be used to model the crystal structure of metals. Together, atoms form structural patterns that repeat and form a crystal. Each brick type can be thought of forming a certain structure type. When combined, the bricks form a final product made of repeating 2 × 2 or 2 × 3 patterns.

### Creative Applications

1. Metals fall into two common **cubic** arrangement structures, just like the Legos limited to 2 x 2 and 2 x 3 bricks. Name these two arrangements.

2. What are the main characteristics of the two common arrangements you just named?

3. 2 x 2 bricks can be combined with 2 x 3 bricks. Can the same be said of the two arrangements with each other? If so, what quality must vary in order for metals to adopt both structures?

4. Almost all common metals are polycrystalline. What does this word mean? What other materials besides metals fall into this category?

5. There is a third common arrangement that metals follow. Name this arrangement.