What is hydrogen's electron configuration?

Hydrogen's electron configuration is 1s1. This means its single electron occupies the 1s orbital in the first principal energy level (n = 1). It is the simplest possible electron configuration of any element.

What are the four quantum numbers for hydrogen's electron?

The four quantum numbers are: principal quantum number n = 1 (first shell), azimuthal quantum number l = 0 (s orbital), magnetic quantum number ml = 0 (only one s orientation), and spin quantum number ms = +1/2 (spin-up by convention).

Why does hydrogen's electron go into the 1s orbital?

The 1s orbital has the lowest energy of all atomic orbitals. By the Aufbau principle, electrons fill the lowest available energy level first. Hydrogen has only one electron, so it occupies the ground-state 1s orbital.

Can hydrogen's electron have ms = -1/2 instead of +1/2?

Yes. For an isolated hydrogen atom in its ground state, both spin orientations (+1/2 and -1/2) are energetically equivalent — there is no external magnetic field to distinguish them. By convention we write +1/2, but either value is physically valid.

What is the abbreviated electron configuration of hydrogen?

Because hydrogen has no noble-gas core to abbreviate, its full and abbreviated configurations are identical: 1s1. There is no preceding noble gas to use as a shorthand bracket.

How does hydrogen's configuration relate to its position on the periodic table?

Hydrogen sits in Period 1 (n = 1) and, by convention, in Group 1 (or sometimes Group 17). Its 1s1 configuration means it has one electron in the s-block, consistent with its Period 1, Group 1 placement.

Hydrogen Electron Configuration

Explore hydrogen's 1s1 electron configuration, orbital box diagram, all four quantum numbers, and key atomic properties in one interactive reference.

Shell Visualization

Animated Bohr model — 1 electron orbiting the nucleus in shell n = 1.

Electron Configuration

1s 1

Principal level (n)

Orbital type

Electrons

Orbital Box Diagram

↑ ↓

One spin-up electron (m_s = +½) in the 1s orbital.
The box has one vacant spin-down slot.

Quantum Numbers

Symbol	Name	Value	Meaning
n	Principal	1	First energy shell — closest to the nucleus.
l	Azimuthal	0	l = 0 denotes an s orbital (spherical shape).
m_l	Magnetic	0	Only one orientation for l = 0 (no directionality).
m_s	Spin	+½	Spin-up electron (convention; −½ is equally valid).

Key Atomic Properties

Atomic Number (Z) 1 1 proton, 1 electron

Atomic Mass 1.008 atomic mass units (u)

Electronegativity 2.20 Pauling scale

1st Ionization Energy 13.598 eV (1312 kJ/mol)

Electron Affinity 0.754 eV (72.8 kJ/mol)

Orbital Radius (Bohr) 52.9 pm (a₀ = 0.529 Å)

Principles Applied

1
Aufbau Principle
Electrons fill orbitals from lowest to highest energy. The 1s orbital has the lowest energy, so hydrogen's electron goes there first.
2
Pauli Exclusion Principle
No two electrons in the same atom can share all four identical quantum numbers. With only one electron, this constraint is automatically satisfied.
3
Hund's Rule
Electrons in degenerate orbitals occupy separate orbitals with parallel spins before pairing. Hydrogen has only one electron, so Hund's rule is trivially satisfied.

Summary

Hydrogen is the simplest atom in the periodic table, with a single electron occupying the 1s orbital. Its full electron configuration is written as 1s1, meaning the electron is in the first principal energy level (n = 1), in an s-type orbital (l = 0). This tool displays the orbital box diagram, all four quantum numbers, and key atomic properties as a structured interactive reference.

How it works

The page loads hydrogen's fixed electron configuration (1s1) automatically.
Review the static shell and orbital diagrams alongside the quantum-number table.
The orbital box diagram shows the single 1s electron with its spin-up arrow.
The quantum number table lists n, l, ml, and ms for the lone electron.
The properties panel shows atomic number, mass, electronegativity, and ionization energy.
Use the configuration, diagrams, and property cards together as a compact reference.

Use cases

Quickly verify hydrogen's electron configuration for chemistry homework.
Study the four quantum numbers using the simplest possible example.
Use as a reference when building up configurations for heavier elements (Aufbau principle).
Understand why hydrogen can act as both a metal (losing its electron) and a nonmetal (gaining one).
Teach introductory atomic structure with a minimal, unambiguous example.
Compare hydrogen's orbital diagram with helium (1s2) side by side.
Review ionization energy concepts — hydrogen has the simplest one-electron case.
Prepare for AP Chemistry or university-level quantum mechanics coursework.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu