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Mobile App Chapter 1: Problem 3
Write the electronic configurations for \({ }_{11} \mathrm{Na},{ }_{13} \mathrm{Al},{ }_{15} \mathrm{P},{ }_{16} \mathrm{~S}\), and \({ }_{18} \mathrm{Ar}\).
Short Answer
Expert verified
Na: 1s^2 2s^2 2p^6 3s^1; Al: 1s^2 2s^2 2p^6 3s^2 3p^1; P: 1s^2 2s^2 2p^6 3s^2 3p^3; S: 1s^2 2s^2 2p^6 3s^2 3p^4; Ar: 1s^2 2s^2 2p^6 3s^2 3p^6
Step by step solution
01
Understanding Electron Configuration
Electron configuration describes the distribution of electrons in an atom's orbitals. Orbitals are defined by principal quantum numbers (n) and sublevels (s, p, d, f). The Aufbau principle, Pauli exclusion principle, and Hund’s rule are key in determining electron configurations.
02
Sodium ({ }_{11} \text{Na})
Start with Sodium (Na) with an atomic number of 11. Distribute 11 electrons among the orbitals:1. 1s can hold 2 electrons: 1s^22. 2s can hold 2 electrons: 2s^23. 2p can hold 6 electrons: 2p^64. 3s can hold 1 electron: 3s^1Therefore, the electron configuration of Na is: 1s^2 2s^2 2p^6 3s^1
03
Aluminum ({ }_{13} \text{Al})
Next is Aluminum (Al) with an atomic number of 13. Distribute 13 electrons among the orbitals:1. 1s^22. 2s^23. 2p^64. 3s^25. 3p^1Therefore, the electron configuration of Al is: 1s^2 2s^2 2p^6 3s^2 3p^1
04
Phosphorus ({ }_{15} \text{P})
Next is Phosphorus (P) with an atomic number of 15. Distribute 15 electrons among the orbitals:1. 1s^22. 2s^23. 2p^64. 3s^25. 3p^3Therefore, the electron configuration of P is: 1s^2 2s^2 2p^6 3s^2 3p^3
05
Sulfur ({ }_{16} \text{S})
Next is Sulfur (S) with an atomic number of 16. Distribute 16 electrons among the orbitals:1. 1s^22. 2s^23. 2p^64. 3s^25. 3p^4Therefore, the electron configuration of S is: 1s^2 2s^2 2p^6 3s^2 3p^4
06
Argon ({ }_{18} \text{Ar})
Finally, Argon (Ar) has an atomic number of 18. Distribute 18 electrons among the orbitals:1. 1s^22. 2s^23. 2p^64. 3s^25. 3p^6Therefore, the electron configuration of Ar is: 1s^2 2s^2 2p^6 3s^2 3p^6
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
The Aufbau Principle
The Aufbau principle is the starting point for determining electron configurations. It states that electrons fill atomic orbitals from the lowest energy level to the highest. Think of orbitals as seats in a theater; they fill from the front row to the back row.
- Start with the 1s orbital, the lowest energy level, which can accommodate 2 electrons.
- Next, fill the 2s orbital, then the 2p, and so on.
- You fill each orbital in the order of increasing energy until all electrons are placed.
Pauli Exclusion Principle
The Pauli exclusion principle further refines how electrons are distributed among orbitals. It states that no two electrons in an atom can have the same set of four quantum numbers.
- Each orbital can hold a maximum of two electrons.
- These two electrons must have opposite spins, represented by the quantum spin numbers +1/2 and -1/2.
Hund's Rule
Hund's rule applies when electrons occupy orbitals of the same energy level, such as p, d, or f orbitals. According to this rule, electrons will fill empty orbitals singly first before pairing up.
- This minimizes electron-electron repulsion, leading to a more stable configuration.
- Imagine a bus: passengers prefer empty seats before sitting next to someone.
Quantum Numbers
Quantum numbers are like the address system for electrons within an atom. They specify the position and energy of each electron. The four quantum numbers are:
- Principal Quantum Number (n): Indicates the main energy level or shell, represented by positive integers (1, 2, 3, ...).
- Angular Momentum Quantum Number (l): Specifies the shape of the orbital (s, p, d, f), with values from 0 to n-1.
- Magnetic Quantum Number (ml): Indicates the orientation of the orbital in space, ranging from -l to +l.
- Spin Quantum Number (ms): Denotes the spin of the electron, either +1/2 or -1/2.
Atomic Orbitals
Atomic orbitals are regions around the nucleus where electrons are likely to be found. They come in different shapes and orientations, defined by the angular momentum quantum number (l).
- s Orbitals: Spherical and centered around the nucleus. Each energy level has one s orbital.
- p Orbitals: Dumbbell-shaped and oriented along three axes (x, y, z). Each energy level from n=2 has three p orbitals.
- d Orbitals: Clover-shaped with 5 possible orientations. They begin at the third energy level (n=3).
- f Orbitals: Complex shapes with 7 orientations, starting from n=4.
