What is the electron configuration of yttrium?

Yttrium (Y, Z=39) has the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹ 5s². Its 39 electrons fill nine subshells. The condensed notation is [Kr] 4d¹ 5s².

What is the noble-gas shorthand for yttrium?

The condensed notation is [Kr] 4d¹ 5s², where [Kr] represents the filled krypton core (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶, Z=36). Only the 4d¹ and 5s² subshells appear explicitly.

Why is yttrium classified as a transition metal?

Yttrium has a partially filled 4d subshell in its ground state (4d¹), which satisfies the IUPAC definition of a d-block element. It opens the second row of transition metals (Period 5, Group 3) just as scandium opens the first row.

What ion does yttrium commonly form?

Yttrium almost exclusively forms Y³⁺ by losing its two 5s and one 4d electrons, reaching the stable [Kr] configuration. The +3 state is strongly favored — yttrium rarely shows any other oxidation state.

How many valence electrons does yttrium have?

Yttrium has 3 valence electrons: two in 5s and one in 4d. These are the electrons involved in bonding and ionization.

What block and period is yttrium in?

Yttrium is in Period 5, Group 3, and belongs to the d-block of the periodic table. It is directly below scandium (Z=21) and exhibits very similar chemistry.

Is yttrium a rare-earth element?

Yttrium is often grouped with the rare-earth elements in practice because it shares similar ionic size and chemical behavior with the lanthanides. However, strictly by IUPAC definition it is a d-block transition metal, not an f-block lanthanide.

Yttrium Electron Configuration

Name: Yttrium Electron Configuration
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Author: Nham Vu

Interactive reference for yttrium's electron configuration (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹ 5s²), noble-gas shorthand [Kr] 4d¹ 5s², orbital diagram, and quantum numbers.

Z = 39 Y Yttrium

Yttrium — Electron Configuration

Atomic number 39 · Transition metal · Period 5, Group 3 · d-block

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹ 5s² [Kr] 4d¹ 5s² 39 electrons 3 valence e⁻

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 (filled)	10	10	3d¹⁰
4s	s orbital, shell n=4	2	2	4s²
4p	p orbitals, shell n=4	6	6	4p⁶
4d	d orbitals, shell n=4 (first d e⁻)	1	10	4d¹
5s	s orbital, shell n=5 (valence)	2	2	5s²
Total		39

Full Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹ 5s²

All subshells written explicitly. Total: 39 electrons.

Noble-Gas Shorthand

[Kr] 4d¹ 5s²

[Kr] = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ (krypton core, Z=36).

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 4d¹ 9 / 32 electrons (28%)

Shell 5 (n=5) — 5s² 2 / 50 electrons (4%)

Shell 4 can hold up to 32 electrons (4s + 4p + 4d + 4f). Yttrium uses only 9: filled 4s² and 4p⁶, plus one lone 4d electron. The 5s fills before 4d in Aufbau order, so 5s² appears alongside 4d¹ in the ground state.

Yttrium as the Opening Member of the Second Transition Series

With Z=39, yttrium places the first electron into the 4d subshell, just as scandium (Z=21) opened the 3d series. Both elements sit in Group 3 and share the [noble gas] d¹ s² pattern. Yttrium invariably forms Y³⁺ in compounds — losing 5s² and 4d¹ to reach the [Kr] core — and is mined alongside lanthanides because its ionic radius (90 pm for Y³⁺) is nearly identical to those of the heavy rare-earth elements.

Orbital Box Diagram

2 electrons (paired) — filled

6 electrons across 3 orbitals — filled

2 electrons (paired) — filled

6 electrons across 3 orbitals — filled

10 electrons across 5 orbitals — fully filled

2 electrons (paired) — filled

6 electrons across 3 orbitals — filled (krypton core ends here)

_ _

1 electron in the first d orbital — 4 orbitals empty

2 electrons (paired) — valence shell

Each box represents one orbital. Opposing arrows represent paired electrons (spin +½ and −½). The lone 4d¹ electron (spin up, blue border) defines yttrium's transition-metal character. All 39 electrons below the 4d¹ come from the filled krypton core.

Quantum Numbers for All 39 Electrons

Electron #	n	l	mₗ	mₛ	Subshell
1	1	0	0	+½	1s
2	1	0	0	−½	1s
3	2	0	0	+½	2s
4	2	0	0	−½	2s
5	2	1	-1	+½	2p
6	2	1	-1	−½	2p
7	2	1	0	+½	2p
8	2	1	0	−½	2p
9	2	1	1	+½	2p
10	2	1	1	−½	2p
11	3	0	0	+½	3s
12	3	0	0	−½	3s
13	3	1	-1	+½	3p
14	3	1	-1	−½	3p
15	3	1	0	+½	3p
16	3	1	0	−½	3p
17	3	1	1	+½	3p
18	3	1	1	−½	3p
19	4	0	0	+½	4s
20	4	0	0	−½	4s
21	3	2	-2	+½	3d
22	3	2	-2	−½	3d
23	3	2	-1	+½	3d
24	3	2	-1	−½	3d
25	3	2	0	+½	3d
26	3	2	0	−½	3d
27	3	2	1	+½	3d
28	3	2	1	−½	3d
29	3	2	2	+½	3d
30	3	2	2	−½	3d
31	4	1	-1	+½	4p
32	4	1	-1	−½	4p
33	4	1	0	+½	4p
34	4	1	0	−½	4p
35	4	1	1	+½	4p
36	4	1	1	−½	4p
37	5	0	0	+½	5s
38	5	0	0	−½	5s
39	4	2	-2	+½	4d

n = principal quantum number; l = azimuthal (l=0 → s, l=1 → p, l=2 → d); mₗ = magnetic; mₛ = spin. Electron 39 (4d¹, highlighted) is yttrium's lone d electron — the defining feature of its transition-metal character.

Summary

Interactive reference for yttrium's electron configuration (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹ 5s²), noble-gas shorthand [Kr] 4d¹ 5s², orbital diagram, and quantum numbers.

How it works

The Aufbau principle fills subshells from lowest to highest energy: 1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d.
Yttrium's 39 electrons fill through the filled krypton core (Z=36) and then place two electrons in 5s and one in 4d.
5s fills before 4d in the ground state because 5s is lower in energy for this region of the periodic table.
The single 4d¹ electron marks yttrium as the first d-block transition metal of Period 5 (Group 3).
Noble-gas shorthand replaces the krypton core (1s² through 4p⁶) with [Kr]: [Kr] 4d¹ 5s².
Use the tabs below to explore the subshell table, orbital box diagram, and element data.

Use cases

Quick reference for chemistry homework or periodic-table exam questions on Period 5 transition metals.
Understand why yttrium forms Y³⁺ by losing its 5s² and 4d¹ electrons.
Compare yttrium's [Kr] 4d¹ 5s² with scandium's [Ar] 3d¹ 4s² to see Period 4/5 analogy.
Verify quantum numbers for each of yttrium's 39 electrons.
Teaching aid for Aufbau principle, d-block filling order, and noble-gas shorthand.
Study how the 4d subshell fills across the second transition series (Y through Cd).
Understand yttrium's role in rare-earth-adjacent chemistry and YAG laser crystals.

Frequently Asked Questions

Last updated: 2026-07-08 · Reviewed by Nham Vu

Yttrium Electron Configuration

Yttrium — Electron Configuration

Subshell Breakdown

Shell Fill Summary

Yttrium as the Opening Member of the Second Transition Series

Orbital Box Diagram

Quantum Numbers for All 39 Electrons

Identity

Physical Properties

Electronic Properties

Context & Uses

Summary

How it works

Use cases

Frequently Asked Questions

What is the electron configuration of yttrium?

What is the noble-gas shorthand for yttrium?

Why is yttrium classified as a transition metal?

What ion does yttrium commonly form?

How many valence electrons does yttrium have?

What block and period is yttrium in?

Is yttrium a rare-earth element?