MULATION Electron Configurations: Box Notation [References) 1A 4p H 3d 2A 4s Li Be 3A 4A 5A 6A 7A 8A B C N O F Ne 3p Al Si P S Cl Ar 3s Na Mg 3B 4B 5B 6B 7B 8B 1B 2B K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 2p 2s Fill All Clear 1s Instructions: Add either a single electron or a pair of electrons to an orbital by clicking and dragging the arrow symbol onto the orbital box. To remove electrons from an orbital, click on the orbital box. Give the “box notation” (also called the “dash notation”) electron configuration of P by filling electrons into the orbital spaces provided. Press Check when complete. Recheck (1 of 5) Show Approach 6th attempt Incorrect The diagram has the wrong number of electrons. This element has 15 electrons.
The Correct Answer and Explanation is:
Phosphorus (P) has an atomic number of 15, which means it has 15 electrons. These electrons fill the orbitals in order of increasing energy according to the Aufbau principle, Hund’s rule, and the Pauli exclusion principle.
✅ Correct Box (Dash) Notation for Phosphorus (15 electrons):
CopyEdit1s ↑↓
2s ↑↓
2p ↑↓ ↑ ↑
3s ↑↓
3p ↑ ↑ ↑
✅ Written Electron Configuration in Box Notation:
- 1s² → two electrons in the 1s orbital (↑↓)
- 2s² → two electrons in the 2s orbital (↑↓)
- 2p⁶ → six electrons in the three 2p orbitals (↑↓ ↑↓ ↑↓)
- 3s² → two electrons in the 3s orbital (↑↓)
- 3p³ → three electrons in the three 3p orbitals (↑ ↑ ↑), one in each box with parallel spins
Total: 2 + 2 + 6 + 2 + 3 = 15 electrons
🔍 Explanation
Phosphorus is located in group 5A and period 3 of the periodic table. This places it in the third energy level and indicates that it has five valence electrons. The electron configuration must account for all 15 electrons.
Electrons fill orbitals from lowest to highest energy. The first two go into the 1s orbital, next two into the 2s, then six into the 2p. This totals ten electrons. The next two fill the 3s orbital. That brings us to 12 electrons. The final three electrons go into the 3p orbitals.
According to Hund’s Rule, electrons fill orbitals of the same sublevel singly before pairing up. That’s why the three 3p electrons each occupy their own orbital with parallel spins. This minimizes electron-electron repulsion and increases stability.
The box notation is a visual method of showing this arrangement using boxes or dashes to represent orbitals and arrows to represent electrons. Each box can hold two arrows pointing in opposite directions. An up arrow (↑) and a down arrow (↓) represent two electrons with opposite spins.
Common mistakes include adding too many or too few electrons, skipping orbitals, or pairing electrons in a sublevel too early. For phosphorus, stopping at 3p³ ensures the total is 15 and that rules of electron configuration are followed.
