ELECTRONIC STRUCTURE: Drawing a box diagram of the electron configuration of an atom Draw the electron configuration for a neutral atom of phosphorus. Energy: Explore: Check
The Correct Answer and Explanation is:
To draw the box diagram (orbital diagram) for a neutral atom of phosphorus (P), follow its atomic number, which is 15. This means phosphorus has 15 electrons.
Electron Configuration:
The electron configuration for phosphorus is:
1s² 2s² 2p⁶ 3s² 3p³
This shows how electrons are distributed among the orbitals.
Box (Orbital) Diagram:
Each box represents an orbital, and each arrow represents an electron. Arrows pointing up and down indicate paired electrons with opposite spins. Orbitals fill in order of increasing energy:
1s → 2s → 2p → 3s → 3p
Here’s the correct orbital (box) diagram:
CopyEdit1s 2s 2p 3s 3p
↑↓ ↑↓ ↑↓↑↓↑↓ ↑↓ ↑ ↑ ↑
- 1s and 2s each hold 2 electrons (↑↓)
- 2p has 6 electrons (↑↓ ↑↓ ↑↓)
- 3s holds 2 electrons (↑↓)
- 3p has 3 electrons, so one arrow goes in each of the three 3p orbitals (↑ ↑ ↑), unpaired and same spin due to Hund’s Rule
Explanation
Phosphorus has an atomic number of 15, meaning it contains 15 protons and, in a neutral atom, 15 electrons. The arrangement of these electrons follows the principles of quantum mechanics: Aufbau Principle, Pauli Exclusion Principle, and Hund’s Rule.
The Aufbau Principle states that electrons occupy the lowest energy orbitals first. Starting from 1s, orbitals are filled in a specific order based on energy levels. After 1s and 2s are filled, electrons go into the 2p orbitals, then 3s, and finally 3p.
The Pauli Exclusion Principle specifies that an orbital can hold a maximum of two electrons with opposite spins. This is represented in box diagrams as one up arrow (↑) and one down arrow (↓) per box when both electrons occupy the same orbital.
Hund’s Rule plays a key role in orbitals like 2p and 3p that contain multiple degenerate (equal energy) orbitals. It states that electrons will fill empty orbitals singly before pairing up. Therefore, in the 3p sublevel of phosphorus, three electrons will each occupy separate orbitals, and all will have parallel spins (same direction arrows), which is more stable.
The result is a clearly structured diagram showing how electrons occupy orbitals based on energy, spin, and sublevel capacity. This diagram helps visualize how phosphorus achieves a stable ground-state electron configuration and plays a vital role in predicting its chemical behavior.
