Heli

Heli (He)

chemical element with symbol He and atomic number 2; rare gas
Atomic Number2
Atomic Weight4.002602
Rhif màs4
Group18
Period1
Blocks
Proton2 p+
Niwtron2 n0
Electron2 e-
Animated Bohr model of He (Heli)

Nodwedd Ffisegol

Atomic Radius
120 pm
molar volume
covalent radius
46 pm
Metallic Radius
ionic radius
Crystal Radius
Van der Waals radius
140 pm
density
0.000164 g/cm³
Atomic Radii Of The Elements: Heli0102030405060708090100110120130140pmAtomic RadiusCovalent RadiusMetallic RadiusVan der Waals radius

Nodwedd Gemegol

egni
proton affinity
177.8 kJ/mol
electron affinity
ionization energy
24.587387936 eV/particle
ionization energy of He (Heli)
enthalpy of vaporization
0.08 kJ/mol
enthalpy of fusion
standard enthalpy of formation
Electron
plisgyn yr electron2
Bohr model: He (Heli)
valence electron2
Lewis structure: He (Heli)
trefn yr electronnau1s2
Enhanced Bohr model of He (Heli)
Orbital Diagram of He (Heli)
Cyflwr ocsidiad
Electronegatifedd
Electrophilicity Index
0.0674191963846371 eV/particle
cyflwr sylfaenol mater
cyflwr materGas
gaseous state of matterMonoatomic
Boiling Point
4.222 K
Melting Point
critical pressure
0.22746 MPa
critical temperature
5.195 K
triple point
2.177 K
5.043 kPa
appearance
lliw
Colorless
appearancecolorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
Mynegrif plygiant
1.000035
nodwedd ffisegol gwrthrych
Thermal Conductivity
0.152 W/(m K)
thermal expansion
molar heat capacity
20.786 J/(mol K)
Specific Heat Capacity
5.193 J/(g⋅K)
heat capacity ratio5/3
electrical properties
type
dargludedd trydanol
Gwrthedd
superconductivity
magnetism
typediamagnetic
magnetic susceptibility (Mass)
-0.0000000059 m³/Kg
magnetic susceptibility (Molar)
-0.0000000000236 m³/mol
magnetic susceptibility (Volume)
-0.00000000105
magnetic ordering
Curie temperature
Néel temperature
strwythur
Crystal StructureFace Centered Cubic (HEX)
lattice constant
3.57 Å
Lattice Anglesπ/2, π/2, π/2
nodwedd mecanyddol deunyddiau
hardness
bulk modulus
shear modulus
Young's modulus
Poisson's ratio
speed of sound
970 m/s
classification
CategoryNoble gases, Noble gases
CAS GroupVIII
IUPAC GroupVIIIA
Glawe Number1
Mendeleev Number112
Pettifor Number1
Geochemical Classvolatile
Goldschmidt classificationatmophile

other

Gas Basicity
148.5 kJ/mol
polarizability
1.38375 ± 0.00002 a₀
C6 Dispersion Coefficient
1.42 a₀
allotrope
Neutron cross section
0.007
Neutron Mass Absorption
0.00001
quantum number1S0
space group225 (Fm_3m)

Isotopes of Helium

Stable Isotopes2
Unstable Isotopes6
Natural Isotopes2
Isotopic Composition4100.00%4100.00%30.00%30.00%

3He

Rhif màs3
neutron number1
relative atomic mass
3.01602932197 ± 0.00000000006 Da
g-factor
-4.25525062 ± 0.00000006
natural abundance
0.0002 ± 0.0002
Dadfeilio ymbelydrolstable isotope
Hanner oesNot Radioactive ☢️
spin1/2
nuclear quadrupole moment
0
dyddiad darganfod1934
parity+

4He

Rhif màs4
neutron number2
relative atomic mass
4.00260325413 ± 0.00000000016 Da
g-factor
0
natural abundance
99.9998 ± 0.0002
Dadfeilio ymbelydrolstable isotope
Hanner oesNot Radioactive ☢️
spin0
nuclear quadrupole moment
0
dyddiad darganfod1908
parity+

5He

Rhif màs5
neutron number3
relative atomic mass
5.012057224 ± 0.00002147 Da
g-factor
natural abundance
Dadfeilio ymbelydrol☢️ elfen ymbelydrol
Hanner oes
602 ± 22 ys
spin3/2
nuclear quadrupole moment
dyddiad darganfod1937
parity-

decay modeintensity
n (neutron emission)100%

6He

Rhif màs6
neutron number4
relative atomic mass
6.018885889 ± 0.000000057 Da
g-factor
0
natural abundance
Dadfeilio ymbelydrol☢️ elfen ymbelydrol
Hanner oes
806.92 ± 0.24 ms
spin0
nuclear quadrupole moment
0
dyddiad darganfod1936
parity+

decay modeintensity
β (β decay)100%
β d (β-delayed deuteron emission)0.000278%

7He

Rhif màs7
neutron number5
relative atomic mass
7.027990652 ± 0.000008115 Da
g-factor
natural abundance
Dadfeilio ymbelydrol☢️ elfen ymbelydrol
Hanner oes
2.51 ± 0.07 zs
spin3/2
nuclear quadrupole moment
dyddiad darganfod1967
parity

decay modeintensity
n (neutron emission)100%

8He

Rhif màs8
neutron number6
relative atomic mass
8.033934388 ± 0.000000095 Da
g-factor
0
natural abundance
Dadfeilio ymbelydrol☢️ elfen ymbelydrol
Hanner oes
119.5 ± 1.5 ms
spin0
nuclear quadrupole moment
0
dyddiad darganfod1965
parity+

decay modeintensity
β (β decay)100%
β n (β-delayed neutron emission)16%
β t (β-delayed triton emission)0.9%

9He

Rhif màs9
neutron number7
relative atomic mass
9.043946414 ± 0.000050259 Da
g-factor
natural abundance
Dadfeilio ymbelydrol☢️ elfen ymbelydrol
Hanner oes
2.5 ± 2.3 zs
spin1/2
nuclear quadrupole moment
0
dyddiad darganfod1987
parity

decay modeintensity
n (neutron emission)100%

10He

Rhif màs10
neutron number8
relative atomic mass
10.052815306 ± 0.000099676 Da
g-factor
0
natural abundance
Dadfeilio ymbelydrol☢️ elfen ymbelydrol
Hanner oes
260 ± 40 ys
spin0
nuclear quadrupole moment
0
dyddiad darganfod1994
parity+

decay modeintensity
2n (2-neutron emission)100%
Helium discharge tube

hanes

darganfyddwr neu ddyfeisiwrSir William Ramsey, Nils Langet, P.T.Cleve
man darganfodScotland/Sweden
dyddiad darganfod1895
geirdarddiadGreek: hêlios (sun).
ynganiadHEE-li-em (Saesneg)

source

Abundance
Abundance in Earth's crust
0.008 mg/kg
natural abundance (cefnfor)
0.000007 mg/L
natural abundance (corff dynol)
natural abundance (Awyrfaen)
natural abundance (Haul)
23 %
Abundance in Universe
23 %

Nuclear Screening Constants

1s0.3125