Finding the Identity of an Unknown Ion

Question

An unknown ion with a charge of +1 has the following electron configuration:

[Ar] 4s⁰ 3d⁵ 4p⁵

What is the identity of the unknown ion?

Answer 1

Hi! So, the cool thing about electron configurations is that they tell you exactly how many electrons there are, therefore you can just count them up! Since you are using the noble gas notation [Ar] you'll start there. Looking at a periodic table, we see that Ar has 18 electrons. Then, you look at your superscripts of 0, 5, and 5. Now, add them up! 18+0+5+5= 28. That means we are dealing with an ion with a +1 charge and 28 electrons. In order to find the identity of an atom, we need to know it's number of protons. Electrons are negative and we have 28 of them, therefore our ion has 29 protons to get that +1 charge (29 positive charges - 28 negative charges = +1). Use your p-table to find the element with the atomic number of 29 and you have your answer! (Cu⁺¹)