The penultimate and outermost orbit of an element contains 10 and 2 electrons, respectively. If the — Atomic Structure Chemistry Question

💡 Solution & Explanation

The outermost orbit is the fourth orbit (n = 4) and contains 2 electrons, which corresponds to 4s^2. The penultimate orbit is the third orbit (n = 3) and contains 10 electrons. In the third shell, the subshells are 3s, 3p, and 3d. Since 3s and 3p are fully filled first (3s^2 3p^6 = 8 electrons), the remaining 10 - 8 = 2 electrons reside in the 3d subshell (3d^2). The core shells (n = 1 and n = 2) are completely filled with 2 (1s^2) and 8 (2s^2 2p^6) electrons, respectively. Total number of electrons = 2 (n=1) + 8 (n=2) + 10 (n=3) + 2 (n=4) = 22 electrons. Thus, the atomic number of the element is 22 (titanium).