2
He
4.0026
Helium (He)
Element 2 · Period 1 · Group 18
noble-gas
gas at room temp
p-block
About Helium
The second most abundant element. Noble gas that remains liquid at absolute zero pressure.
Physical Properties
Atomic Mass
4.0026 u
State at 25°C
Gas
Melting Point
-272.2 °C
Boiling Point
-268.93 °C
Density
0.0001785 g/cm³
Magnetism
Diamagnetic
Atomic Properties
Electron Configuration
1s²
Electron Shells
2
Atomic Radius
31 pm
Ionization Energy
2372 kJ/mol
Oxidation States
0
Discovery & History
Discovered By
Pierre Janssen, Norman Lockyer
Discovery Year
1868
Named By
Norman Lockyer
Name origin: Greek: Helios (Sun)
Frequently Asked Questions
- Is Helium a metal, nonmetal, or metalloid?
- Helium is classified as a noble-gas.
- What state is Helium in at room temperature?
- Helium is a gas at standard room temperature (25°C).
- What is the atomic mass of Helium?
- Helium has an atomic mass of 4.0026 atomic mass units (u).
- Who discovered Helium?
- Helium was discovered by Pierre Janssen, Norman Lockyer in 1868.
- Where is Helium on the periodic table?
- Helium is element number 2, located in period 1 and group 18.