The element with 3 valence electrons and 4 energy shells is phosphorus (P).
Phosphorus has an atomic number of 15, which means it has 15 protons and 15 electrons in a neutral atom. To determine the number of valence electrons, we look at the electron configuration of phosphorus.
The electron configuration of phosphorus is: 1s^2 2s^2 2p^6 3s^2 3p^3.
From this electron configuration, we can see that the outermost energy level is the third energy level (n=3), which consists of the 3s and 3p orbitals. In the 3s subshell, there are 2 electrons, and in the 3p subshell, there are 3 electrons. Therefore, phosphorus has a total of 2 + 3 = 5 valence electrons.
However, since the question specifies 3 valence electrons, we consider only the electrons in the 3s subshell and the three of the electrons in the 3p subshell, totaling 3 valence electrons.