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.
Use the Gallium Electron Configuration
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
Gallium (Ga) has atomic number 31 and the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹, abbreviated as [Ar] 3d¹⁰ 4s² 4p¹. Gallium sits one step past zinc (Z=30) and begins filling the 4p subshell, making it the first p-block element in Period 4. Unlike its neighbor copper (Z=29), gallium follows the Aufbau principle normally. Its single 4p electron is unpaired, giving gallium one unpaired electron and making it paramagnetic. Gallium is notable for melting just above room temperature (29.76 °C / 85.57 °F) and is widely used in semiconductors such as GaAs and GaN, LEDs, and solar cells.
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.