---
title: "Hydrogen (H): Atomic Mass, Electron Configuration & Properties"
url: https://www.moldraw.com/elements/hydrogen.html
description: "Hydrogen (H), element 1: atomic mass 1.008, electron configuration 1s¹, group 1, period 1, s-block reactive nonmetal. Melting and boiling point, density, electronegativity and shells."
lang: en
publisher: Scidart Academy
generated: 2026-11-03
---
1H1.008

# Hydrogen (H) – element 1

Hydrogen is a chemical element with the symbol **H** and atomic number **1**. It is a reactive nonmetal in group 1, period 1 of the periodic table (s-block), and is a gas at room temperature.

Hydrogen (H) has atomic number 1, atomic mass 1.008 u and electron configuration 1s1.

[Download periodic table PDF](https://www.moldraw.com/printables/periodic-table.pdf)[Open interactive periodic table](https://www.moldraw.com/tools/free-chem-tools/interactive-periodic-table.html)

## Hydrogen facts

| Symbol | H |
| --- | --- |
| Atomic number | 1 |
| Atomic mass | 1.008 u (g/mol) |
| Category | reactive nonmetal |
| Group | group 1 |
| Period | 1 |
| Block | s-block |
| Phase at 20 °C | Gas |
| Electron configuration | 1s1 |
| Noble-gas notation | 1s1 |
| Electrons per shell | 1 |
| Valence electrons | 1 |

## Bohr model and shells

Hydrogen has 1 electrons in 1 shell: 1. Full configuration and noble-gas notation are in the table; work out any element or ion with the [electron configuration calculator](https://www.moldraw.com/tools/free-chem-tools/electron-configuration-calculator.html).

## Physical and atomic properties

| Melting point | 13.99 K (-259.2 °C) |
| --- | --- |
| Boiling point | 20.271 K (-252.9 °C) |
| Density | 0.08988 g/L |
| Electronegativity (Pauling) | 2.2 |
| Electron affinity | 72.769 kJ/mol |
| Ionization energies | 1312 kJ/mol (1st) |
| Molar heat capacity | 28.836 J/(mol·K) |
| Discovered by | Henry Cavendish |

Use the atomic mass in the [molar mass calculator](https://www.moldraw.com/tools/free-chem-tools/molar-mass-calculator.html) for any formula containing H.

## Position in the periodic table

Tap any element to open its page.

## Molecules with hydrogen

- [Acetic acid](https://www.moldraw.com/molecules/acetic-acid.html)
- [Acetone](https://www.moldraw.com/molecules/acetone.html)
- [Acetylene](https://www.moldraw.com/molecules/acetylene.html)
- [Adenine](https://www.moldraw.com/molecules/adenine.html)
- [Adrenaline](https://www.moldraw.com/molecules/adrenaline.html)
- [Alanine](https://www.moldraw.com/molecules/alanine.html)
- [Ammonia](https://www.moldraw.com/molecules/ammonia.html)
- [Aspirin](https://www.moldraw.com/molecules/aspirin.html)
- [ATP](https://www.moldraw.com/molecules/atp.html)
- [Benzene](https://www.moldraw.com/molecules/benzene.html)
- [Caffeine](https://www.moldraw.com/molecules/caffeine.html)
- [Chloroform](https://www.moldraw.com/molecules/chloroform.html)

Rotate each one in 3D, or draw your own structure in [MolDraw](https://www.moldraw.com/).

## Frequently asked questions

### What is the atomic mass of hydrogen?

The atomic mass of hydrogen is 1.008 u, so one mole of hydrogen atoms weighs 1.008 g.

### What is the electron configuration of hydrogen?

Hydrogen has 1 electrons: 1s¹, or 1s¹ in noble-gas notation. Electrons per shell: 1.

### How many valence electrons does hydrogen have?

Hydrogen has 1 valence electron (group 1).

### Is hydrogen a metal?

No. Hydrogen is a nonmetal (reactive nonmetal).

### Where is hydrogen on the periodic table?

Hydrogen is in group 1, period 1, in the s-block.

Data: [Periodic-Table-JSON](https://github.com/Bowserinator/Periodic-Table-JSON) (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.