Helium

Helium is the second element in the periodic table. It is a colorless, odorless, non-toxic, and inert gas. Helium has the simplest atomic structure, consisting of just two protons and two neutrons. This element is the second most abundant element in the universe, primarily found in stars and gas giant planets. Helium plays a crucial role in various applications, such as cryogenics, balloons, and as a coolant in nuclear reactors.

Overview

English Name:

Helium

Latin Name:

Helium

Year Discovered:

1868

Discovered By:

Pierre Janssen and Norman Lockyer

Group:

Period:

Electrons:

CAS Number:

7440-59-7

Cost Per 100 Grams:

$0.08

Atomic Properties

Electronic Configuration:

1s²

Ion Charge:

Ionisation Energies:

2372.3 kJ/mol

Atomic Radius (Empirical):

31 pm

Atomic Radius (Calculated):

49 pm

Covalent Radius:

28 pm

Van Der Waals Radius:

140 pm

Ionisation Potential of An Atom:

24.5874 eV

Electrons Per Layer:

Atomic Multiplicities Of The Gas:

Atomic Weight:

4.003

Oxidation States

Reactivity

Electron Affinity:

-48 kJ/mol

Valence:

Electronegativity:

4.16

Thermal Properties

Melting Point:

0.95 K

Boiling Point:

4.22 K

Critical Point:

Pressure: 0.227 MPa

Temperature: 5.19 K

Thermal Conductivity:

0.1513 W/(m·K)

Heat Capacity:

Specific: 5.193 J/(g·K)

Molar: 20.786 J/(mol·K)

Thermal Coefficient:

0.000208

Enthalpy:

Fusion: 0.0138 kJ/mol

Vaporisation: 0.0845 kJ/mol

Atomization: 0 kJ/mol

Curie Temperature:

N/A

Neel Temperature:

N/A

Superconductivity Point:

N/A

Physical and Chemical Properties

State of matter (25° C/ 77°F):

Gas

Density:

Gas: 0.1785 g/L

Molar Volume (Vmol):

22.41 L/mol

Speed of Sound (Vs):

972 m/s

Hardness:

N/A

Bulk Modulus (K):

4 GPa

Shear Modulus (G):

N/A

Young's Modulus (E):

N/A

Color:

Colorless

Brinell Hardness (MPa):

N/A

Liquid Density (Kg/m^3):

124.7 kg/m³

Hardness of Mohs:

N/A

Refractive Index:

1.000035

Vickers Hardness (MPa):

N/A

Crystal Structure:

Face-centered cubic

Electromagnetic Properties

Electrical Type:

Insulator

Resistivity:

10^15 Ω·m

Magnetic Type:

Diamagnetic

Superconductivity:

Not applicable

Volume Magnetic Susceptibility:

-0.00009

Mass Magnetic Susceptibility:

-0.00005

Molar Mass Susceptibility:

-0.00020

Electrical Conductivity:

6.93 × 10^-39 S/m

Mass (γ_mass):

6.646 × 10^-27 kg

Mass (γ_mol):

4.003 × 10^-26 mol

Volume (γ_vol):

22.414 L

Grid Parameters

Crystal Structure:

Face-centered cubic

Grid Parameters:

0.355 nm

Attitude:

N/A

Debye Temperature:

27.1 K

Safety and Precautions

Signal Word:

Warning

Hazard Statements:

H280

Precautionary Statements:

P403, P501

RTECS Number:

Not available

Risk:

Flammability: Non-flammable
Health Risk: Asphyxiant
Reactivity: Stable
Specific Risk: None

Importance

Main sources:

Natural gas, air separation

Main Usage:

Cryogenics, balloons, welding

Nuclear Properties

Radioactive:

Isotopes:

He-3, He-4

Neutron Cross Sectional:

0.00334 barns

Half Life (s):

Stable

Lifetime:

Stable

Prevalence

Universe:

23%

Sun:

Oceans:

0.00005%

Humans:

7 ppm

Earth's Crust:

0.008 ppm

Meteorites:

0.2%