Answer
Selenium.
Work Step by Step
The element in the fourth period with four 4p electrons has an electron configuration of $[Ar]4s^{2}3d^{10}4p^{4}$, which corresponds to the element selenium.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.