Practice question · Multiple choice
Atomic radius decreases across a period even though electrons are being added. Why does adding electrons make the atom smaller?
Hints
- Ask what happens to the number of protons as you move right.
- Do the new electrons go into a new shell or the same one?
Show the answer
B. Because the nuclear charge rises while the shell stays
Why
Nuclear charge grows faster than shielding within a period. Down a group the trend reverses, because a genuinely new shell is added and distance wins.
Practise Chemical periodicity
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