Practice question · Multiple choice
Why does atomic radius decrease from left to right across a period?
Hints
- Ask what changes in the nucleus, and where the new electrons go.
- Same shell, poor mutual shielding, so the growing nuclear charge wins.
Show the answer
A. Nuclear charge rises while the added electrons shield each other poorly
Why
Each step adds a proton and an electron, but the electron joins the same shell where it screens the nucleus only weakly. The net pull on the outer shell therefore grows and the atom contracts.
Practise Periodic Properties
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