Question

The atom of an element X has 15 protons 15 electrons and 16 neutrons in it (a) what is the atomic number of X (b) what is the mass number of X (c)what is the number of valence electrons in X?

Answer 1

(a) 15= number of protons
(b) 31= the combination of protons and neutrons
(c) 3= if you check the periodic table for the element with the atomic number 15 it’s P, and group 5A, has 3 valence electrons