Question

A natural atom possesses the atomic number of 13 and a atomic mass of 27. Three electrons are lost. From what region of the atom are they lost?

Answer 1

The electrons are lost from the valence shell (outermost electron shell) of the atom.

Step-by-step explanation:

This is able to be inferred not only because valence electrons being lost first is a trend but also because the atom in question has actually 3 valence electrons (13-2-8 = 3).