How many electrons does the ion31 315 P − contain?A. 12B. 15C. 16D. 18Page 11 of 77

The ion 31 15 P - is an isotope of phosphorus. The superscript 31 is the atomic mass number (protons + neutrons), and the subscript 15 is the atomic number (number of protons).

Step 1: Identify the number of protons. The atomic number is 15, so there are 15 protons.

Step 2: Identify the charge of the ion. The "-" sign indicates that the ion has a negative charge, which means it has gained an electron.

Step 3: Calculate the number of electrons. In a neutral atom, the number of protons equals the number of electrons. However, since this ion has a negative charge, it has one extra electron.

So, the number of electrons in the ion 31 15 P - is 15 (from the protons) + 1 (from the extra electron due to the negative charge) = 16 electrons.

Therefore, the correct answer is C. 16.