Ionic radius: why charge matters
Losing or gaining electrons changes electron repulsion and effective nuclear attraction, often changing ion size strongly.
Start with the idea
Losing or gaining electrons changes electron repulsion and effective nuclear attraction, often changing ion size strongly.
A concrete example
Na⁺ is smaller than Na in common models, while Cl⁻ is larger than Cl.
Mendeleev’s tip
Do not start with a formula. Identify what changes, what stays constant and which quantity you are trying to explain or calculate.
Go one step deeper
Within an isoelectronic series, more protons attract the same number of electrons more strongly, so radius tends to decrease.
A trend or model is not an exceptionless law. Always check the quantity’s definition and the conditions being compared.
Check your understanding
Can you explain the phenomenon in your own words before looking at an equation?