Write the electronic configurations of the elements with the atomic numbers 61, 91, 101, and 109.
The electronic configurations are:
Atomic Number 61 (Promethium): [Xe] 4f⁵ 6s²
Atomic Number 91 (Protactinium): [Rn] 5f² 6d¹ 7s²
Atomic Number 101 (Mendelevium): [Rn] 5f¹³ 7s²
Atomic Number 109 (Meitnerium): [Rn] 5f¹⁴ 6d⁷ 7s²
Explanation
The question asks for electronic configurations of four elements. From the provided context, the Actinoid table directly gives configurations for elements 91 and 101. For element 91 (Protactinium), the table shows 5f² 6d¹ 7s². For element 101 (Mendelevium), the table shows 5f¹³ 7s². For element 61 (Promethium), it is a lanthanoid - the context mentions lanthanoids have 'variable occupancy of 4f level' with '6s² common', and element 61 would have 4f⁵ 6s² configuration. For element 109, it belongs to the 6d series (after actinoids end at 103), following the d-block filling pattern shown in the context for transition elements.
Solution Steps
Step 1: Identify element 61 as a lanthanoid with 4f orbital filling. Based on the pattern mentioned in context (4f level filling with 6s² common), configuration is [Xe] 4f⁵ 6s².
Step 2: Read element 91 (Protactinium) configuration directly from Actinoid table: [Rn] 5f² 6d¹ 7s².
Step 3: Read element 101 (Mendelevium) configuration directly from Actinoid table: [Rn] 5f¹³ 7s².
Step 4: For element 109, recognize it's in the 6d series after actinoids. Following d-block filling pattern from context, configuration is [Rn] 5f¹⁴ 6d⁷ 7s².