Helium - Wikipedia
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.
Helium atom - Wikipedia
A helium atom is an atom of the chemical element helium. Helium is composed of two electrons bound by the electromagnetic force to a nucleus containing two protons along with two neutrons, depending on the isotope, held together by the strong force.
Helium - Element information, properties and uses
Element Helium (He), Group 18, Atomic Number 2, s-block, Mass 4.003. Sources, facts, uses, scarcity (SRI), podcasts, alchemical symbols, videos and images.
Helium | Definition, Properties, Uses, & Facts | Britannica
2024年10月25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.
Lecture 22: Helium Atom‡. Now that we have treated the Hydrogen-like atoms in some detail, we now proceed to discuss the next-simplest system: the Helium atom. In this situation, we have two 6z electrons – with coordinates r1 and r2 – orbiting a nucleus with. r charge Z = 2located at the point R. Now, for the hydrogen.
helium - NIST Chemistry WebBook
Formula: He. Molecular weight: 4.002602. IUPAC Standard InChI: InChI=1S/He. IUPAC Standard InChIKey: SWQJXJOGLNCZEY-UHFFFAOYSA-N. CAS Registry Number: 7440-59-7. Chemical structure: This structure is also available as a 2d Mol file. Permanent link for this species. Use this link for bookmarking this species for future reference.
8: Helium Atom - Chemistry LibreTexts
2016年12月25日 · The lowest excitated state of helium is represented by the electron configuration 1s 2s. The 1 s 2 p configuration has higher energy, even though the 2 s and 2 p orbitals in hydrogen are degenerate, because the 2 s penetrates closer to the nucleus, where the potential energy is more negative.
Helium Facts (Atomic Number 2 or He) - ThoughtCo
2021年9月2日 · Helium is atomic number 2 on the periodic table, with the element symbol He. It is a colorless, flavorless gas, best known for its use in filling floating balloons. Here is a collection of facts about this lightweight, interesting element:
Periodic Table of Elements: Los Alamos National Laboratory
Isotopes. Seven isotopes of helium are known: Liquid helium (He-4) exists in two forms: He-4I and He-4II, with a sharp transition point at 2.174K. He-4I (above this temperature) is a normal liquid, but He-4II (below it) is unlike any other known substance.
Helium, Chemical Element - structure, uses, elements, metal, gas ...
Its atoms consist of two protons, two neutrons, and two electrons. Only the hydrogen atom is simpler than a helium atom. The hydrogen atom has one proton, one electron, and no neutrons. Helium was first discovered not on Earth, but in the Sun.