What is the first quantum number of a $1 s^2$ electron in phosphorus, $1 s^2 2 s^2 2 p^6 3 s^2 3 p^3$?
A. $n=1$
B. $n=0$
C. $n=2$
D. $n=3
Answer (2)
The first quantum number for a 1 s 2 electron in phosphorus is n = 1 , indicating it is in the first energy level. Therefore, the correct answer is A. n = 1 .
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The problem asks for the first quantum number of a 1 s 2 electron in phosphorus.
The first quantum number is the principal quantum number 'n'.
For a 1 s 2 electron, n = 1.
Therefore, the answer is n = 1 .
Explanation
Understanding the Problem The question asks for the first quantum number of a 1 s 2 electron in phosphorus, given its electron configuration 1 s 2 2 s 2 2 p 6 3 s 2 3 p 3 . The first quantum number is the principal quantum number, denoted as 'n'.
Identifying the Principal Quantum Number The principal quantum number 'n' corresponds to the energy level of the electron. For a 1 s 2 electron, the principal quantum number is the coefficient of 's', which is 1.
Determining the Answer Therefore, the first quantum number (n) is 1.
Examples
Understanding quantum numbers helps us predict the behavior of electrons in atoms, which is crucial in fields like chemistry and materials science. For example, knowing the electron configuration and quantum numbers allows us to understand how different elements will interact to form chemical bonds, leading to the creation of new materials with specific properties. This knowledge is also essential in developing technologies like semiconductors and solar cells.
