Multiple Choice
What is the electron configuration of phosphorus (P) using [Ne] to represent the configuration of the first 2 periods?
10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following represents the correct electron configuration for the valence electrons of indium (In)?
A
[Kr] 5s² 4d¹⁰ 5p¹
B
[Kr] 5s² 4d⁹ 5p²
C
[Kr] 4d¹⁰ 5s²
D
[Kr] 5s² 5p²
Verified step by step guidance1
Identify the atomic number of indium (In), which is 49. This tells us the total number of electrons in a neutral indium atom.
Recognize that the electron configuration of indium will be based on filling the electron orbitals according to the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level to the highest.
Recall the order of filling for orbitals: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p. Indium's electron configuration will follow this sequence up to its atomic number.
Understand that the valence electrons are those in the outermost shell, which for indium are in the 5s and 5p orbitals. The 4d orbitals are filled before the 5p orbitals.
Write the electron configuration for indium, starting from the nearest noble gas, krypton (Kr), which has an electron configuration of [Kr]. Then, add the electrons in the 5s, 4d, and 5p orbitals: .
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