## Chapter 2, Homework Problem 2.45

Palmquist_Sierra_2N
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### Chapter 2, Homework Problem 2.45

Struggling with the concept of electron configuration. How to do this question with an explanation of how you did it. Thanks.

Which elements are predicted to have the following ground-state electron configurations: a) [Kr] 4d^10 5s^2 5p^4; b) [Ar] 3d^3 4s^2; c) [He]2s^2 2p^2; d) [Rn]7s^2 6d^2

Edward_Lee_3C
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### Re: Chapter 2, Homework Problem 2.45

Since these are ground-state electron configurations means numbers of electrons = number of protons. Add all the electrons in the ground-state electron configuration and find the same number on the periodic table and you will get the element predicted to have that configuration. For example, [Kr] = 36 + 10 (from 4d10) + 2 (from 5s2) + 4 (from 5p4) = 52 which is Tellurium and the correct answer.

Chem_Mod
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### Re: Chapter 2, Homework Problem 2.45

So the question asks you to find the ground state element (meaning neutral atom) following the electron configuration. So by applying what Professor Lavelle taught on electron configuration and element table in class, this problem should be able to solved (and I encourage you to have your periodic table in front of you while reading the next part). For [Kr] 4d^10 5s^2 5p^4, [Kr] can be defined as a shorthand notation of the electron configuration for Kr, and the "4d^10 5s^2 5p^4" is placement of electrons in the atomic orbital following [Kr]. We see that the 4d and 5s orbitals after Kr are fully filled with 10 and 2 electrons, but the 5p orbital is not full. This would be the same as placing your finger on the element table starting at Rb ([Kr]5s^1), and moving to the right through the 5s and 4d row. When you reach the 5p row, only four electrons will need to be filled, so moving 4 elements to the right, what element should you get?

Andrea- 3J
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tellurium