- #1
chops369
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Homework Statement
I have a few questions here that say to identify which atom from each pair is larger.
One pair is Be and B, and the other is P and Cl.
Homework Equations
N/A
The Attempt at a Solution
I know that Be is larger than B, and that P is larger than Cl. I'm just having trouble understanding why. Is there some rule of thumb that says that sizes of atoms increase when you go across a period? What is the reasoning behind this?