객관식
Which of the following electron configurations is incorrect?
142
views
10. Periodic Properties of the Elements
The Electron Configuration
객관식
Which of the following electron configurations represents an atom of chlorine (atomic number 17) in an excited state?
A
1s^2 2s^2 2p^6 3s^1 3p^6
B
1s^2 2s^2 2p^6 3s^2 3p^4 4s^1
C
1s^2 2s^2 2p^6 3s^2 3p^6
D
1s^2 2s^2 2p^6 3s^2 3p^5
검증된 단계별 안내1
Recall that the atomic number of chlorine is 17, which means a neutral chlorine atom has 17 electrons.
Write the ground state electron configuration for chlorine by filling orbitals in order of increasing energy: 1s, 2s, 2p, 3s, and then 3p, until all 17 electrons are placed.
The ground state configuration for chlorine is \$1s^2 2s^2 2p^6 3s^2 3p^5$, where the 3p subshell has 5 electrons.
An excited state occurs when one or more electrons are promoted to a higher energy orbital, leaving a lower energy orbital partially filled or less than full.
Compare the given configurations to the ground state: the excited state will have the same total number of electrons (17) but with an electron moved to a higher energy level, such as \$3s^1 3p^6$, indicating an electron promoted from 3s to 3p.
