Question

An ion has a 3- charge and 18 electrons. What is the identity of the element? (Look at your periodic table). A. P B. Ar C. Sc D. Mg

Answer 1

A. P (Phosphorus)

Step-by-step explanation:

We are told our unknown ion has a charge of 3-, despite already having 18 electrons. That means 3 new electrons have joined in for fun. The neutral atom had 15 electrons, so three more would make the charge 3-. A neutral atom with 15 electrons would have the same number of protons, 15. The unknown element is element 15, the fun-loving phosphorus atom, P.