How many electrons does \({31}_{15}\)P\(^3-\) contain?

To determine the number of electrons in \({31}_{15}\)P\(^{3-}\), we need to first understand the notation. The atomic symbol \({31}_{15}\)P represents an atom of phosphorus with an atomic number of 15, which means it has 15 protons in its nucleus. The superscript 3- indicates that the atom has gained 3 electrons, giving it a net charge of -3. When an atom gains electrons, its number of electrons increases by the same number as the magnitude of the charge. Therefore, to determine the number of electrons in \({31}_{15}\)P\(^{3-}\), we can subtract the charge (-3) from the number of protons (15): Number of electrons = Number of protons - Charge Number of electrons = 15 - (-3) = 18 So \({31}_{15}\)P\(^{3-}\) contains 18 electrons. Therefore, the answer to this question is 18.