Practice question · Put in order
Arrange these atoms from LARGEST to smallest atomic radius.
- Oxygen
- Magnesium
- Sodium
- Potassium
Hints
- A step down a group adds a whole shell; a step right removes almost nothing.
- Potassium is below sodium, magnesium is right of sodium, and oxygen is in period 2.
Show the answer
- Potassium
- Sodium
- Magnesium
- Oxygen
Why
K lies below Na and so is largest. Mg is one step right of Na and therefore slightly smaller. O is in period 2 with a high effective nuclear charge and is smallest by a wide margin, moving down a group changes size far more than moving across a period.
Practise Periodic Properties
The app has 3 more questions on this lesson, and keeps your place in the course. Chemistry I is free to start.
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