The electronic configuration of Einsteinium is :

(Given atomic number of Einsteinium $=99$)

<p>The correct option for the electronic configuration of Einsteinium (atomic number 99) is:</p> <strong>Option C: [Rn] 5f¹¹ 6d⁰ 7s²</strong> <p>Here's why:</p> <ol> <li><strong>Atomic Number and Electrons:</strong> Einsteinium has an atomic number of 99, which means it has 99 protons in its nucleus. Since atoms are neutral, it also has 99 electrons surrounding the nucleus.</li><br> <li><strong>Electron Shells:</strong> Electrons fill up energy shells around the nucleus. The order of filling follows the Aufbau principle, which generally fills lower energy shells before moving to higher ones.</li><br> <li><strong>Noble Gas Core Notation:</strong> The notation [Rn] represents the filled electron configuration of Radon (atomic number 86). This is a shorthand to avoid writing out the entire configuration of the inner shells, as they are not involved in the chemical behavior of Einsteinium.</li><br> <li><strong>Filling the f-orbital:</strong> Einsteinium is an actinide element, located in the f-block of the periodic table. The 5f subshell fills up after the 6s subshell.</li><br> <li><strong>Aufbau Principle:</strong> According to the Aufbau principle, the 5f subshell can hold up to 14 electrons. In Einsteinium, 11 electrons fill the 5f subshell (5f¹¹).</li><br> <li><strong>Empty d-orbital:</strong> The 6d subshell has a higher energy level than the 5f subshell. Since the 5f subshell isn't completely filled, the 6d subshell remains empty (6d⁰).</li><br> <li><strong>Outermost Electrons:</strong> The remaining two electrons fill the outermost 7s subshell (7s²).</li> </ol> <p>Therefore, the complete electronic configuration of Einsteinium is:</p> <strong>[Rn] 5f¹¹ 6d⁰ 7s²</strong>