Gallium Electron Configuration
Reference tool for gallium's electron configuration (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹), abbreviated as [Ar] 3d¹⁰ 4s² 4p¹, with orbital box diagram, subshell table, and element facts.
Gallium — Electron Configuration
Atomic number 31 · p-block metal · Period 4, Group 13 · Post-transition metal
Subshell Breakdown
| Subshell | Type | Electrons | Max Capacity | Notation |
|---|---|---|---|---|
| 1s | s orbital, shell n=1 | 2 | 2 | 1s² |
| 2s | s orbital, shell n=2 | 2 | 2 | 2s² |
| 2p | p orbitals, shell n=2 | 6 | 6 | 2p⁶ |
| 3s | s orbital, shell n=3 | 2 | 2 | 3s² |
| 3p | p orbitals, shell n=3 | 6 | 6 | 3p⁶ |
| 3d | d orbitals, shell n=3 | 10 | 10 | 3d¹⁰ |
| 4s | s orbital, shell n=4 | 2 | 2 | 4s² |
| 4p | p orbitals, shell n=4 | 1 | 6 | 4p¹ |
| Total | 31 | |||
Full Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹
All subshells written explicitly.
Abbreviated (Noble-Gas)
[Ar] 3d¹⁰ 4s² 4p¹
[Ar] = 1s² 2s² 2p⁶ 3s² 3p⁶ (18 electrons).
Valence Electrons
4s² 4p¹ = 3 e⁻
Three outer electrons lost to form Ga³⁺.
Shell Fill Summary
Shells 1–3 are completely filled. Shell 4 has 4s filled and 4p partially filled (1 of 6); the 4d and 4f subshells are empty at ground state.
Period 4 Neighbors
| Element | Z | Configuration | Unpaired e⁻ | Follows Aufbau? |
|---|---|---|---|---|
| Copper (Cu) | 29 | [Ar] 3d¹⁰ 4s¹ | 1 | No (anomaly) |
| Zinc (Zn) | 30 | [Ar] 3d¹⁰ 4s² | 0 | Yes |
| Gallium (Ga) ← this element | 31 | [Ar] 3d¹⁰ 4s² 4p¹ | 1 | Yes |
| Germanium (Ge) | 32 | [Ar] 3d¹⁰ 4s² 4p² | 2 | Yes |
Copper (Z=29) is anomalous: it promotes one 4s electron to 3d for a fully filled 3d¹⁰ subshell. Zinc fills 3d¹⁰ and 4s² normally. Gallium is the first Period 4 element to begin filling the 4p subshell, following the Aufbau principle exactly.
Gallium in the Periodic Table
Gallium is the first p-block element in Period 4. After the d-block fills across elements 21–30, gallium (Z=31) adds one electron to the 4p subshell, beginning the sequence that ends with krypton (Z=36, 4p⁶).
The single 4p electron is unpaired, giving gallium one unpaired electron and making it paramagnetic. Gallium's most common ion is Ga³⁺, formed by losing all three valence electrons (4s² 4p¹), leaving the stable [Ar] 3d¹⁰ core.
Gallium's notably low melting point (29.76 °C) means it liquefies in a warm hand. This is due to its unusual orthorhombic crystal structure, which features covalent Ga₂ dimers rather than typical close-packed metallic bonding — a direct consequence of its position at the p-block boundary.
Summary
Reference tool for gallium's electron configuration (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹), abbreviated as [Ar] 3d¹⁰ 4s² 4p¹, with orbital box diagram, subshell table, and element facts.
How it works
- The Aufbau principle fills subshells in order of increasing energy: 1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p.
- The [Ar] core (1s² 2s² 2p⁶ 3s² 3p⁶) represents 18 electrons identical to the argon noble-gas configuration.
- 4s fills before 3d because 4s has slightly lower energy at lower atomic numbers.
- After the 3d subshell fills completely at zinc (Z=30), gallium adds one electron to the 4p subshell.
- Total electrons: 2 + 2 + 6 + 2 + 6 + 10 + 2 + 1 = 31, matching gallium's atomic number.
- Use the tabs below to explore the subshell table, orbital box diagram, and element properties.
Use cases
- Quickly verify gallium's full or abbreviated configuration for homework and exams.
- Understand why gallium has one unpaired electron and is paramagnetic.
- Use the [Ar] 3d¹⁰ 4s² 4p¹ shorthand when writing configurations in inorganic chemistry.
- Compare gallium with neighboring zinc (3d¹⁰ 4s², 0 unpaired) and germanium (3d¹⁰ 4s² 4p², 2 unpaired).
- Visualize the start of the 4p subshell filling across the p-block of Period 4.
- Teaching aid for Aufbau principle, p-block elements, and post-transition metal behavior.