Elements can be categorized into four blocks based on their number of electron orbitals:

* s-block: Elements in this block have their outermost electron in an *s* orbital.

* p-block: Elements in this block have their outermost electron in a *p* orbital.

* d-block: Elements in this block have their outermost electron in a *d* orbital.

* f-block: Elements in this block have their outermost electron in an *f* orbital.

Let me know if you want to know more about each block!