Here's why:

* Electron Configuration: The electron configuration of antimony is [Kr] 4d¹⁰ 5s² 5p³.

* Valence Shell: The valence shell is the outermost electron shell, which in this case is the 5th shell (n=5).

* Valence Electrons: The electrons in the valence shell are the valence electrons. Sb has 2 electrons in the 5s subshell and 3 electrons in the 5p subshell, for a total of 5 valence electrons.