Question

(30 points) What is the relationship between the atomic numbers and atomic radii of the elements in the group? Propose an explanation for this relationship? Is this consistent with the periodic trends you’ve learned about?

**y is atomic radius and x is atomic number**

Answer 1

The relationship is r = 2.5Z + 130.

From your graph, I estimate the slope of the line to be:

`\text{slope} = (\Delta y )/(\Delta x ) = (260-130)/(56-4) = (130)/(52) = 2.5\\`

The y-intercept ≈ 130.

So, the equation for the line is

r = 2.5Z + 130.

The relation tells us that the atomic size increases as the atomic number increases.

This makes sense because, as you go down a Group, you are adding electrons to the next shell further out.