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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Billy1500 on December 07, 2014, 10:38:39 PM

Title: Periodic Trends: Atomic Radii
Post by: Billy1500 on December 07, 2014, 10:38:39 PM

I just had a general question about the atomic radii trend on the periodic table. Why does the d-block ignore the periodic trend? I look at the d-block on a 3D visual of a periodic table with the radii trend but I can't seem to figure anything out. Does it have something to do with electrons being added to the core and not to the outer shell?

Thanks to anyone who answers.

Title: Re: Periodic Trends: Atomic Radii
Post by: AdityaDev on December 11, 2014, 09:22:29 PM

Have you heard about lanthanide contractions? That's the reason.
The effect results from poor shielding of nuclear charge (nuclear attractive force on electrons) by 4f electrons; the 6s electrons are drawn towards the nucleus, thus resulting in a smaller atomic radius.