Question

The element Neodymium (Nd) belongs to the 4f series. What is its atomic number?

• A. 60
• B. 61
• C. 62
• D. 63

Hint:

When identifying atomic numbers of lanthanides, note that they follow a sequential order from Cerium (58) to Lutetium (71). Memorizing a few key elements can help navigate the series quickly.

Answer 1

The Correct Option is A

Step 1: Understand the problem and define key concepts.
We need to find the atomic number of Neodymium (Nd), which belongs to the 4f series. The atomic number is the number of protons in an element’s nucleus, uniquely identifying it in the periodic table. The 4f series refers to the lanthanide series, where the 4f subshell is progressively filled. Step 2: Identify the 4f series (lanthanides).
The 4f series includes the lanthanide elements, with atomic numbers ranging from 58 to 71. Some key elements in this series are:
Cerium (Ce, 58)
Praseodymium (Pr, 59)
Neodymium (Nd, 60)
Promethium (Pm, 61)
Samarium (Sm, 62)
Europium (Eu, 63)
\ldots
Lutetium (Lu, 71) Neodymium must have an atomic number within this range. Step 3: Determine the atomic number of Neodymium.
Listing the lanthanides in order:
Atomic number 58: Cerium (Ce)
Atomic number 59: Praseodymium (Pr)
Atomic number 60: Neodymium (Nd)
Atomic number 61: Promethium (Pm) Thus, Neodymium (Nd) has an atomic number of 60. Step 4: Confirm Neodymium belongs to the 4f series.
The electron configuration of Neodymium (atomic number 60) is: \[ [\text{Xe}] 6s^2 4f^4 5d^1 \] where \( [\text{Xe}] \) represents the configuration of Xenon (atomic number 54). The presence of electrons in the \( 4f \) subshell (\( 4f^4 \)) confirms that Neodymium is part of the 4f series. Step 5: Match with the given options.
Comparing with the options:
(A) 60: Matches Neodymium’s atomic number.
(B) 61: Promethium (Pm).
(C) 62: Samarium (Sm).
(D) 63: Europium (Eu). The correct option is (A) 60. Step 6: Verify the result.
Neodymium is positioned between Praseodymium (Z = 59) and Promethium (Z = 61) in the lanthanide series, confirming its atomic number as 60. Its electron configuration also aligns with the 4f series. Final Answer in a Box \[ {60} \]