Hydrogen (H): electron configuration, atomic mass and facts
Hydrogen (H) is element 1 of the periodic table, a reactive nonmetal in period 1, group 1. Its electron configuration is 1s1, with electrons arranged in shells 1, and its standard atomic weight is 1.008 u.
💡 The lightest element. Hydrogen fusion powers the Sun.
▶ Watch Hydrogen’s electrons orbit in the interactive periodic tableHydrogen at a glance
| Symbol | H |
|---|---|
| Atomic number | 1 |
| Atomic mass | 1.008 u |
| Category | Reactive nonmetal |
| Group | 1 |
| Period | 1 |
| Block | s-block |
| Electron configuration | 1s1 |
| Noble-gas shorthand | 1s1 |
| Electrons per shell | 1 |
| Outer-shell electrons | 1 |
| Electronegativity (Pauling) | 2.2 |
| State at 20 °C | gas |
Experiments with hydrogen
🧪 Acid–base titration
Find the end-point of HCl vs NaOH with phenolphthalein and plot the titration curve.
🐘 Elephant's toothpaste
Iodide-catalysed decomposition of 30% hydrogen peroxide produces a towering, steaming foam.
🫧 CO₂ and limewater
Marble + acid makes CO₂. Bubble it through limewater: milky, then clear again in excess.
⚡ Electrolysis of water
Split water in a Hofmann voltameter: twice as much hydrogen as oxygen.
Where is Hydrogen on the periodic table?
Hydrogen is in period 1, group 1, in the s-block. The period number matches its 1 electron shell, and the block names the subshell its last electrons fill. In the same group, Lithium sits directly below it. Hydrogen is placed at the top of group 1 because it has one outer electron, but it behaves as a nonmetal, not like the alkali metals below it.
How to work out the electron configuration of Hydrogen
Put 1 electron into subshells in order of rising energy, filling each before starting the next: 1s¹ (1).
How electronegative is Hydrogen?
Hydrogen has a Pauling electronegativity of 2.2, ranking 17 of the 100 elements with a known value (fluorine is highest at 3.98). That is in the middle of the range.
Hydrogen in the virtual lab
Faradium’s chemistry workbench includes these chemicals that contain hydrogen: Baking soda, Sodium hydroxide pellets, Slaked lime, Ammonium chloride, Ammonium nitrate, Copper sulfate crystals, Iron(II) sulfate crystals, Malachite, Sugar (sucrose), Distilled water, Dilute hydrochloric acid, Hydrochloric acid 0.1 M, Conc. hydrochloric acid, Dilute sulfuric acid, Conc. sulfuric acid, Dilute nitric acid, Conc. nitric acid, Ethanoic acid (vinegar), Sodium hydroxide, Sodium hydroxide 0.1 M, Potassium hydroxide, Limewater, Barium hydroxide, Ammonia solution, Sodium hydrogencarbonate, Hydrogen peroxide 6%, Hydrogen peroxide 30%, Ethanol, Hydrogen cylinder, Ammonia cylinder, Hydrogen chloride. Open the Chemistry Lab to experiment with them.
Frequently asked questions
What is the electron configuration of Hydrogen?
The electron configuration of Hydrogen (H) is 1s1. In noble-gas shorthand it is written 1s1.
How many electrons does Hydrogen have in each shell?
Hydrogen has 1 electrons arranged in shells as 1. It has 1 electron in its outer shell.
What is the atomic mass of Hydrogen?
The standard atomic weight of Hydrogen is 1.008 u, so one mole of Hydrogen atoms has a mass of about 1.008 g.
Is Hydrogen a metal?
No. Hydrogen is a reactive nonmetal.
Explore nearby elements
More reactive nonmetals: Carbon, Nitrogen, Oxygen, Phosphorus, Sulfur, Selenium. See all elements on the periodic table.