Why are #"actinides"# and #"lanthanides"# not placed into Groups?

1 Answer
Feb 26, 2017

Answer:

#"f-element metals"# do not follow the Group numbers......

Explanation:

......they are a class of metals all by themselves, and they have a peculiar chemistry, which is marked by extreme Lewis-acidity. They commonly form #M^(3+)# ions. Because the Group 3 metals, scandium, and yttrium, also commonly form #M^(3+)# ions, their chemistry is often lumped together with that of the lanthanides.