Interactive periodic table showing names, electrons, and oxidation states. Visualize trends, 3D orbitals, isotopes, and mix compounds. Fully descriptive writeups.

Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.

2025年1月17日 · helium (He), chemical element, inert gas of Group 18 (noble gases) of the periodic table. The second lightest element (only hydrogen is lighter), helium is a colourless, odourless, and tasteless gas that becomes liquid at −268.9 °C (−452 °F). The boiling and freezing points of helium are lower than those of any other known substance.

Helium is the 2nd element in the periodic table and has a symbol of He and atomic number of 2. It has an atomic weight of 4.00260 and a mass number of 4. Helium has two protons and two neutrons in its nucleus, and two electrons in one shell.

Helium is the second most abundant element in the universe and is primarily produced because of radioactive decay. It was discovered in 1868 by Jules Janssen and Norman Lockyer. The discovery of helium is linked with its primary sources, the sun.

Periodic Table element Summary Helium. Helium is a chemical element with symbol He and atomic number 2. Classified as a noble gas, Helium is a gas at room temperature.

In this comprehensive guide, you'll learn about Helium's unique chemical and physical properties, trends in the periodic table, isotopes, and its historical significance. We'll also cover its abundance, crystal structure, electron configuration, and health & safety guidelines.