What are inner transition elements? Decide which of the following atomic numbers are the atomic numbers of the inner transition elements: 29, 59, 74, 95, 102, 104.
Inner transition elements are elements in which the last electron enters the -orbital. The two series of inner transition elements—lanthanoids and actinoids—constitute the -block of the periodic table.
From the given atomic numbers, the inner transition elements are: 59, 95, and 102.
Atomic number 59 belongs to the lanthanoid series (4f-block). Atomic numbers 95 (Americium) and 102 belong to the actinoid series (5f-block). The other atomic numbers—29 (Copper, d-block), 74 (d-block transition element), and 104 (d-block)—are not inner transition elements as they belong to the d-block of transition elements.
Explanation
The textbook defines inner transition elements as the two series (lanthanoids and actinoids) that constitute the f-block. The context provides a table showing actinoids from atomic number 89-101, confirming that 95 (Americium) is an actinoid. Atomic number 59 falls within the lanthanoid series (57-71), and 102 is also an actinoid. The d-block transition elements table shows atomic number 29 (Cu) as a d-block element, not an f-block element.
Solution Steps
Step 1: Define inner transition elements as f-block elements (lanthanoids and actinoids)
Step 2: Identify lanthanoid range (atomic numbers 57-71) and actinoid range (atomic numbers 89-103)
Step 3: Check each atomic number: 29 (d-block), 59 (lanthanoid), 74 (d-block), 95 (actinoid - Americium), 102 (actinoid), 104 (d-block)
Step 4: Select 59, 95, and 102 as inner transition elements