【Daily Question】Theoretical Foundation 2020.06.23
Thread Content
Multiple-choice question: The ground-state valence electron configuration of a certain element is 4d15S2. Its position in the periodic table is: ( ) (A) Fourth period, VB ； (B) Fifth period, IVB ； (C) Fourth period, IIIB ； (D) Fifth period, IIIB. Answer: D. Hint: Extra points will be given to those who can explain the solution process; the answer can be seen in the response
D. According to the rules of electron configuration, the electron arrangement of the ground-state atom of this element is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d1 5s2. It can be seen that this element’s atom has 39 electrons, 5 electron shells, and 2 electrons in its outermost shell. Based on the electron configuration of the ground-state atom, this element is located in period 5, group IIIB of the periodic table
D Explanation: D. The outer electron configuration is 4d15s2, which corresponds to the element Y; it belongs to group IIIB in period 5, so D is correct；