2 He Helium 4.0026 u

Helium

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आवर्त
1
समूह
18
ब्लॉक
s-ब्लॉक
अवस्था (STP)
Gas

Helium is the second lightest and second most abundant element in the universe. It is an inert noble gas used in cryogenics and as a lifting gas.

दिखावट: Colorless gas

About Helium

Chemically inert and second only to hydrogen in lightness, helium fills atomic number 2 with an atomic mass of 4.0026. Its two electrons complete the 1s shell, a closed configuration reflected in an exceptionally high ionization energy of 2372 kJ/mol and the absence of ordinary chemistry. The colorless noble gas remains liquid closer to absolute zero than any other substance, boiling at just 4.2 K. Pierre Janssen first detected it in 1868, in the spectrum of the Sun rather than on Earth. As the second most abundant element in the universe, helium is valued in cryogenics, where its low boiling point is essential, and as a non-flammable lifting gas—both uses resting on the stability that keeps it from bonding. It sits in group 18.

भौतिक गुण

परमाणु द्रव्यमान 4.0026 u
घनत्व 0.0001785 g/cm³
गलनांक -272.2 °C
क्वथनांक -268.9 °C
STP पर अवस्था Gas
परमाणु त्रिज्या 31.0 pm

इलेक्ट्रॉनिक गुण

आयनीकरण ऊर्जा 2372.3 eV
संयोजकता इलेक्ट्रॉन 2

इलेक्ट्रॉन विन्यास

विन्यास 1s²

Electron Shell Configuration

Helium electron shell configuration He 2e⁻

Position in Periodic Table

Helium position in the periodic table He

खोज

द्वारा खोजा गया: Pierre Janssen
वर्ष: 1868

ब्लॉक और आवर्त

ब्लॉक

s p d f

आवर्त

1 2 3 4 5 6 7

आवर्त सारणी

लैंथेनाइड एक्टिनाइड

He से जुड़ी अभिक्रियाएँ

Proton-Proton Chain (Solar Fusion)

4¹H → ⁴He + 2e⁺ + 2νₑ + energy

Nuclear

Deuterium-Tritium Fusion

²H + ³H → ⁴He + ¹n

Nuclear

Alpha Decay of Radium-226

²²⁶Ra → ²²²Rn + ⁴He

Nuclear

Alpha Decay of Polonium-210

²¹⁰Po → ²⁰⁶Pb + ⁴He

Nuclear

Alpha Decay of Uranium-238

²³⁸U → ²³⁴Th + ⁴He

Nuclear
सभी 12 अभिक्रियाएँ देखें →

उत्कृष्ट गैस में और

10 Ne Neon 18 Ar Argon 36 Kr Krypton 54 Xe Xenon 86 Rn Radon

Explore on Science FYI

StarFYI
Sun (Sol)

Helium produced by hydrogen fusion in stellar cores

Frequently Asked Questions

What is Helium?
Helium (He) is a chemical element with atomic number 2. It is a gas at standard temperature and pressure, classified as a उत्कृष्ट गैस.
What are the key properties of Helium?
Helium has an atomic mass of 4.0026 u, density of 0.0001785 g/cm³, melting point of -272.2°C, boiling point of -268.9°C.
What is the electron configuration of Helium?
The electron configuration of Helium is 1s2. It is in the s-block of the periodic table.
Who discovered Helium?
Helium was discovered by Pierre Janssen in 1868.