What is the electron configuration of samarium?

Samarium (Sm, Z=62) has the ground-state configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 4f⁶ 6s². In noble-gas shorthand this is [Xe] 4f⁶ 6s², with 62 total electrons.

What is the noble-gas shorthand for samarium?

The condensed notation is [Xe] 4f⁶ 6s², where [Xe] represents the filled 54-electron xenon core (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶).

How many valence electrons does samarium have?

Samarium has 8 valence electrons: six in the 4f subshell and two in the 6s subshell. Losing two gives Sm²⁺ (uncommon); losing three gives Sm³⁺ (the most stable ion, losing 4f¹ 6s²... or 6s² plus one 4f).

What oxidation states does samarium exhibit?

Samarium primarily forms the +3 oxidation state (Sm³⁺), which is the most common and stable. The +2 state (Sm²⁺) also exists and is more accessible for samarium than for most other lanthanides, because loss of two 6s electrons gives a half-filled 4f⁶ configuration that has some extra stability.

Why does samarium prefer the +3 oxidation state?

Like most lanthanides, samarium preferentially loses its two 6s electrons plus one 4f electron to give Sm³⁺. The +3 state is strongly favored across the lanthanide series due to the stability of the resulting [Xe]-core ion. Sm²⁺ is less common but attainable because the 4f⁶ half-filling provides marginal extra stability.

How do the 4f electrons fill in samarium?

By Hund's rule, electrons fill degenerate orbitals singly with parallel spins before pairing. Samarium's six 4f electrons each occupy a separate 4f orbital (mₗ = −3, −2, −1, 0, +1, +2) with spin +½, leaving the mₗ = +3 orbital empty. This gives a 4f⁶ configuration with spin multiplicity S = 6×½ = 3 (septet ground state with L = 5, J = 0).

What block and period is samarium in?

Samarium is in Period 6 and belongs to the f-block (lanthanide series). It is the sixth lanthanide after lanthanum. Its group number is formally listed under Group 3 in some conventions, though lanthanides are displayed as a separate row below the main periodic table.

What is samarium used for?

Samarium is best known for SmCo₅ and Sm₂Co₁₇ permanent magnets, which are among the strongest known and operate well at high temperatures. It is also used as a neutron absorber in nuclear reactors, in catalysts, and in some laser materials.

Samarium Electron Configuration

Name: Samarium Electron Configuration
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Author: Nham Vu

Interactive reference for samarium's electron configuration ([Xe] 4f⁶ 6s²), orbital box diagram, quantum numbers, oxidation states, and key element data.

Z = 62 Sm Samarium

Samarium — Electron Configuration

Atomic number 62 · Lanthanide (rare earth) · Period 6 · f-block

[Xe] 4f⁶ 6s² 62 electrons 8 valence e⁻ +2, +3 oxidation

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
4s	s orbital, shell n=4	2	2	4s²
3d	d orbitals, shell n=3	10	10	3d¹⁰
4p	p orbitals, shell n=4	6	6	4p⁶
5s	s orbital, shell n=5	2	2	5s²
4d	d orbitals, shell n=4	10	10	4d¹⁰
5p	p orbitals, shell n=5	6	6	5p⁶
4f	f orbitals, shell n=4	6	14	4f⁶
6s	s orbital, shell n=6	2	2	6s²
Total		62

Full Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 4f⁶ 6s²

All subshells written explicitly (62 electrons).

Noble-Gas Shorthand

[Xe] 4f⁶ 6s²

[Xe] = 54-electron xenon core (shells 1–5).

Shell Fill Summary

Shell 1 (n=1) — 1s² 2 / 2 electrons (100%)

Shell 2 (n=2) — 2s² 2p⁶ 8 / 8 electrons (100%)

Shell 3 (n=3) — 3s² 3p⁶ 3d¹⁰ 18 / 18 electrons (100%)

Shell 4 (n=4) — 4s² 4p⁶ 4d¹⁰ 4f⁶ 24 / 32 electrons (75%)

Shell 5 (n=5) — 5s² 5p⁶ 8 / 50 electrons (16%)

Shell 6 (n=6) — 6s² 2 / 72 electrons (3%)

Shell 4 holds 4s², 4p⁶, 4d¹⁰, and 4f⁶ (6 of 14 possible f-electrons). Shells 5 and 6 are only partially filled.

Oxidation States Reference

+3 (primary) Sm³⁺

Loses 6s² and one 4f electron. Most stable and common oxidation state. Configuration becomes [Xe] 4f⁵.

+2 (secondary) Sm²⁺

Loses only the two 6s² electrons. The resulting 4f⁶ configuration provides marginal stability. Accessible in solid-state chemistry.

Orbital Box Diagram (valence shells)

—

6 electrons (all spin-up, unpaired) across 7 orbitals — Hund's rule. 7th orbital is empty.

2 electrons (paired, ±½) — filled

Inner core [Xe]: All 54 xenon-core electrons (shells 1–5, subshells 1s through 5p) are fully paired. Only the 4f and 6s valence subshells are shown above.

Each box represents one orbital. An upward arrow = spin +½; a downward arrow = spin −½. By Hund's rule, the six 4f electrons each occupy a separate orbital before any pairing occurs, maximizing total spin.

Quantum Numbers — Valence Electrons (4f and 6s)

Electron #	n	l	mₗ	mₛ	Subshell
55	4	3	-3	+½	4f
56	4	3	-2	+½	4f
57	4	3	-1	+½	4f
58	4	3	0	+½	4f
59	4	3	1	+½	4f
60	4	3	2	+½	4f
61	6	0	0	+½	6s
62	6	0	0	−½	6s

n = principal quantum number; l = azimuthal (l=3 → f); mₗ = magnetic (−3 to +3 for f); mₛ = spin. Electrons #1–54 form the [Xe] core (not shown).

Summary