Heli (He)
chemical element with symbol He and atomic number 2; rare gas
| Atomic Number | 2 |
|---|---|
| Atomic Weight | 4.002602 |
| Rhif màs | 4 |
| Group | 18 |
|---|---|
| Period | 1 |
| Block | s |
| Proton | 2 p+ |
|---|---|
| Niwtron | 2 n0 |
| Electron | 2 e- |
Nodwedd Ffisegol
| Atomic Radius | |
|---|---|
| molar volume | |
| covalent radius | |
| Metallic Radius | |
| ionic radius | |
| Crystal Radius | |
| Van der Waals radius | |
| density |
Nodwedd Gemegol
| egni | |
|---|---|
| proton affinity | |
| electron affinity | |
| ionization energy | |
| enthalpy of vaporization | |
| enthalpy of fusion | |
| standard enthalpy of formation | |
| Electron | |
| plisgyn yr electron | 2 |
 | |
| valence electron | 2 ⓘ |
 | |
| trefn yr electronnau | 1s2ⓘ |
  | |
| Cyflwr ocsidiad | |
| Electronegatifedd | |
| Electrophilicity Index | |
| cyflwr sylfaenol mater | |
| cyflwr mater | {ERROR}|
| gaseous state of matter | Monoatomic |
| Boiling Point | |
| Melting Point | |
| critical pressure | |
| critical temperature | |
| triple point | |
| appearance | |
| lliw | Black
|
| appearance | colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field |
| Mynegrif plygiant | 1.000035
|
| nodwedd ffisegol gwrthrych | |
| Thermal Conductivity | |
| thermal expansion | |
| molar heat capacity | |
| Specific Heat Capacity | |
| heat capacity ratio | 5/3 |
| electrical properties | |
| type | |
| dargludedd trydanol | |
| Gwrthedd | |
| superconductivity | |
| magnetism | |
| type | diamagnetic |
| 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 Structure | {ERROR} |
| lattice constant | |
| Lattice Angles | π/2, π/2, π/2 |
| nodwedd mecanyddol deunyddiau | |
| hardness | |
| bulk modulus | |
| shear modulus | |
| Young's modulus | |
| Poisson's ratio | |
| speed of sound | |
| classification | |
| Category | Actinides, Noble gases |
| CAS Group | VIII |
| IUPAC Group | VIIIA |
| Glawe Number | 1 |
| Mendeleev Number | 112 |
| Pettifor Number | 1 |
| Geochemical Class | volatile |
| Goldschmidt classification | atmophile |
other
| Gas Basicity | |
|---|---|
| polarizability | |
| C6 Dispersion Coefficient | |
| allotrope | |
| Neutron cross section | 0.007
|
| Neutron Mass Absorption | 0.00001
|
| quantum number | 1S0 |
| space group | 225 (Fm_3m) |
Isotopes of Helium
| Stable Isotopes | 2 |
|---|---|
| Unstable Isotopes | 6 |
| Natural Isotopes | 2 |
3He
| Rhif màs | 3 |
|---|---|
| neutron number | 1 |
| Relative Atomic Mass | |
| g-factor | -4.25525062 ± 0.00000006
|
| natural abundance | 0.0002 ± 0.0002
|
| Dadfeilio ymbelydrol | stable isotope |
| Hanner oes | Not Radioactive ☢️ |
| spin | 1/2 |
| nuclear quadrupole moment | 0
|
| dyddiad darganfod | 1934 |
| parity | + |
4He
| Rhif màs | 4 |
|---|---|
| neutron number | 2 |
| Relative Atomic Mass | |
| g-factor | 0
|
| natural abundance | 99.9998 ± 0.0002
|
| Dadfeilio ymbelydrol | stable isotope |
| Hanner oes | Not Radioactive ☢️ |
| spin | 0 |
| nuclear quadrupole moment | 0
|
| dyddiad darganfod | 1908 |
| parity | + |
5He
| Rhif màs | 5 |
|---|---|
| neutron number | 3 |
| Relative Atomic Mass | |
| g-factor | |
| natural abundance | |
| Dadfeilio ymbelydrol | ☢️ elfen ymbelydrol |
| Hanner oes | 602 ± 22 ys
|
| spin | 3/2 |
| nuclear quadrupole moment | |
| dyddiad darganfod | 1937 |
| parity | - |
| decay mode | intensity |
|---|---|
| n (neutron emission) | 100% |
6He
| Rhif màs | 6 |
|---|---|
| neutron number | 4 |
| Relative Atomic Mass | |
| g-factor | 0
|
| natural abundance | |
| Dadfeilio ymbelydrol | ☢️ elfen ymbelydrol |
| Hanner oes | 806.92 ± 0.24 ms
|
| spin | 0 |
| nuclear quadrupole moment | 0
|
| dyddiad darganfod | 1936 |
| parity | + |
| decay mode | intensity |
|---|---|
| β− (β− decay) | 100% |
| β− d (β−-delayed deuteron emission) | 0.000278% |
7He
| Rhif màs | 7 |
|---|---|
| neutron number | 5 |
| Relative Atomic Mass | |
| g-factor | |
| natural abundance | |
| Dadfeilio ymbelydrol | ☢️ elfen ymbelydrol |
| Hanner oes | 2.51 ± 0.07 zs
|
| spin | 3/2 |
| nuclear quadrupole moment | |
| dyddiad darganfod | 1967 |
| parity |
| decay mode | intensity |
|---|---|
| n (neutron emission) | 100% |
8He
| Rhif màs | 8 |
|---|---|
| neutron number | 6 |
| Relative Atomic Mass | |
| g-factor | 0
|
| natural abundance | |
| Dadfeilio ymbelydrol | ☢️ elfen ymbelydrol |
| Hanner oes | 119.5 ± 1.5 ms
|
| spin | 0 |
| nuclear quadrupole moment | 0
|
| dyddiad darganfod | 1965 |
| parity | + |
| decay mode | intensity |
|---|---|
| β− (β− decay) | 100% |
| β− n (β−-delayed neutron emission) | 16% |
| β− t (β−-delayed triton emission) | 0.9% |
9He
| Rhif màs | 9 |
|---|---|
| neutron number | 7 |
| Relative Atomic Mass | |
| g-factor | |
| natural abundance | |
| Dadfeilio ymbelydrol | ☢️ elfen ymbelydrol |
| Hanner oes | 2.5 ± 2.3 zs
|
| spin | 1/2 |
| nuclear quadrupole moment | 0
|
| dyddiad darganfod | 1987 |
| parity |
| decay mode | intensity |
|---|---|
| n (neutron emission) | 100% |
10He
| Rhif màs | 10 |
|---|---|
| neutron number | 8 |
| Relative Atomic Mass | |
| g-factor | 0
|
| natural abundance | |
| Dadfeilio ymbelydrol | ☢️ elfen ymbelydrol |
| Hanner oes | 260 ± 40 ys
|
| spin | 0 |
| nuclear quadrupole moment | 0
|
| dyddiad darganfod | 1994 |
| parity | + |
| decay mode | intensity |
|---|---|
| 2n (2-neutron emission) | 100% |
hanes
| darganfyddwr neu ddyfeisiwr | Sir William Ramsey, Nils Langet, P.T.Cleve |
|---|---|
| man darganfod | Scotland/Sweden |
| dyddiad darganfod | 1895 |
| geirdarddiad | Greek: hêlios (sun). |
| ynganiad | HEE-li-em (Saesneg) |
source
| Abundance | |
|---|---|
| Abundance in Earth's crust | |
| natural abundance (cefnfor) | |
| natural abundance (corff dynol) | |
| natural abundance (Awyrfaen) | |
| natural abundance (Haul) | 23 %
|
| Abundance in Universe | 23 %
|
Nuclear Screening Constants
| 1 | s | 0.3125 |
