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He Helium
Element Information, Facts, Properties, Trends, Uses, Comparison with other elements

2
He
Helium
Element 2 of Periodic table is Helium with atomic number 2, atomic weight 4.002602. Helium, symbol He, has a Face Centered Cubic structure and Colorless color. Helium is a Noble Gas element. It is part of group 18 (helium family or neon family). Know everything about Helium Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.
2 He - Helium | SchoolMyKids

Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the Noble Gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.

It belongs to group 18 of the periodic table having trivial name noble gases, aerogens.

Helium Facts

Read key information and facts about element Helium

NameHelium
Atomic Number2
Atomic SymbolHe
Atomic Weight4.002602
PhaseGas (Monoatomic Gas )
ColorColorless
Appearancecolorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
ClassificationNoble Gas
Group in Periodic Table18
Group Namehelium family or neon family
Period in Periodic Tableperiod 1
Block in Periodic Tablep -block
Electronic Configuration1s2
Electronic Shell Structure (Electrons per shell)2
Melting Point0 K
Boiling Point4.22 K
CAS NumberCAS7440-59-7
Neighborhood Elements
123456789101112131415161718
1
1
H
Hydrogen
1.008

Atomic #

Electronic Shell #

Symbol
Name
Atomic Weight
HGas
HgLiquid
CSolid
Metals
Metalloids
NonMetals
Alkali metals
Alkali earth metals
Lanthanoids
Transition metals
Post-transition metals
Other nonmetals
Halogens
Nobel gas
Actinoids
2
He
Helium
4.003
2
3
Li
Lithium
6.941
4
Be
Beryllium
9.012
5
B
Boron
10.811
6
C
Carbon
12.011
7
N
Nitrogen
14.007
8
O
Oxygen
15.999
9
F
Fluorine
18.998
10
Ne
Neon
20.180
3
11
Na
Sodium
22.990
12
Mg
Magnesium
24.305
13
Al
Aluminium
26.982
14
Si
Silicon
28.085
15
P
Phosphorus
30.974
16
S
Sulfur
32.065
17
Cl
Chlorine
35.453
18
Ar
Argon
39.948
4
19
K
Potassium
39.098
20
Ca
Calcium
40.078
21
Sc
Scandium
44.956
22
Ti
Titanium
47.867
23
V
Vanadium
50.941
24
Cr
Chromium
51.996
25
Mn
Manganese
54.938
26
Fe
Iron
55.845
27
Co
Cobalt
58.933
28
Ni
Nickel
58.693
29
Cu
Copper
63.546
30
Zn
Zinc
65.409
31
Ga
Gallium
69.723
32
Ge
Germanium
72.640
33
As
Arsenic
74.922
34
Se
Selenium
78.960
35
Br
Bromine
79.904
36
Kr
Krypton
83.798
5
37
Rb
Rubidium
85.468
38
Sr
Strontium
87.620
39
Y
Yttrium
88.906
40
Zr
Zirconium
91.224
41
Nb
Niobium
92.906
42
Mo
Molybdenum
95.940
43
Tc
Technetium
98
44
Ru
Ruthenium
101.070
45
Rh
Rhodium
102.906
46
Pd
Palladium
106.420
47
Ag
Silver
107.868
48
Cd
Cadmium
112.411
49
In
Indium
114.818
50
Sn
Tin
118.710
51
Sb
Antimony
121.760
52
Te
Tellurium
127.600
53
I
Iodine
126.904
54
Xe
Xenon
131.293
6
55
Cs
Cesium
132.905
56
Ba
Barium
137.327
57 - 71
La - Lu
Lanthanides
72
Hf
Hafnium
178.490
73
Ta
Tantalum
180.948
74
W
Tungsten
183.840
75
Re
Rhenium
186.207
76
Os
Osmium
190.230
77
Ir
Iridium
192.217
78
Pt
Platinum
195.078
79
Au
Gold
196.967
80
Hg
Mercury
200.590
81
Tl
Thallium
204.383
82
Pb
Lead
207.200
83
Bi
Bismuth
208.980
84
Po
Polonium
209
85
At
Astatine
210
86
Rn
Radon
222
7
87
Fr
Francium
223
88
Ra
Radium
226
89 - 103
Ac - Lr
Actinides
104
Rf
Rutherfordium
261
105
Db
Dubnium
262
106
Sg
Seaborgium
266
107
Bh
Bohrium
264
108
Hs
Hassium
277
109
Mt
Meitnerium
268
110
Ds
Darmstadtium
281
111
Rg
Roentgenium
272
112
Cn
Copernicium
285
113
Nh
Nihonium
284
114
Fl
Flerovium
289
115
Mc
Moscovium
288
116
Lv
Livermorium
292
117
Ts
Tennessine
294
118
Og
Oganesson
294
Lanthanides
57
La
Lanthanum
138.905
58
Ce
Cerium
140.116
59
Pr
Praseodymium
140.908
60
Nd
Neodymium
144.240
61
Pm
Promethium
145
62
Sm
Samarium
150.360
63
Eu
Europium
151.964
64
Gd
Gadolinium
157.250
65
Tb
Terbium
158.925
66
Dy
Dysprosium
162.500
67
Ho
Holmium
164.930
68
Er
Erbium
167.259
69
Tm
Thulium
168.934
70
Yb
Ytterbium
173.040
71
Lu
Lutetium
174.967
Actinides
89
Ac
Actinium
227
90
Th
Thorium
232.038
91
Pa
Protactinium
231.036
92
U
Uranium
238.029
93
Np
Neptunium
237
94
Pu
Plutonium
244
95
Am
Americium
243
96
Cm
Curium
247
97
Bk
Berkelium
247
98
Cf
Californium
251
99
Es
Einsteinium
252
100
Fm
Fermium
257
101
Md
Mendelevium
258
102
No
Nobelium
259
103
Lr
Lawrencium
262

How to Locate Helium on Periodic Table

Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 2 to find Helium on periodic table.

Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Helium on periodic table look for cross section of group 18 and period 1 in the modern periodic table.

Helium History

The element Helium was discovered by P. Janssen and N. Lockyer in year 1868 in Sweden and United Kingdom. Helium was first isolated by W. Ramsay,T. Cleve, and N. Langlet in 1895. Helium derived its name from the Greek word helios, meaning 'sun'.

Janssen and Lockyer observed independently a yellow line in the solar spectrum that did not match any other element. Years later, Ramsay, Cleve, and Langlet observed independently the element trapped in cleveite about the same time.

Helium Presence: Abundance in Nature and Around Us

The table below shows the abundance of Helium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.

 ppb by weight (1ppb =10^-7 %)ppb by atoms (1ppb =10^-7 %)
Abundance in Universe23000000072000000
Abundance in Sun23000000074000000
Abundance in Meteorites--
Abundance in Earth's Crust5.530
Abundance in Oceans0.00720.011
Abundance in Humans--

Crystal Structure of Helium

The solid state structure of Helium is Face Centered Cubic.

The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.

Unit Cell Parameters

The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)

abc
424.2 pm424.2 pm424.2 pm

and the angles between them Lattice Angles (alpha, beta and gamma).

alphabetagamma
π/2 π/2 π/2

The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.

The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.

Space Group NameFm_ 3m 2 He Helium - Crystal Structure | SchoolMyKids
Oxidation StatesSpace Group Number225
Crystal StructureFace Centered Cubic

Helium Atomic and Orbital Properties

Helium atoms have 2 electrons and the electronic shell structure is [2] with Atomic Term Symbol (Quantum Numbers) 1S0.

Atomic Number2
Number of Electrons (with no charge)2
Number of Protons2
Mass Number4
Number of Neutrons2
Shell structure (Electrons per energy level)2
Electron Configuration1s2
Valence Electrons1s2
Valence (Valency)0
Main Oxidation States-
Oxidation States
Atomic Term Symbol (Quantum Numbers)1S0

Bohr Atomic Model of Helium - Electrons per energy level

2 He Helium - Electron Shell Structure | SchoolMyKids
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Ground State Electronic Configuration of Helium - neutral Helium atom

Abbreviated electronic configuration of Helium

The ground state abbreviated electronic configuration of Neutral Helium atom is 1s2. The portion of Helium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as . For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 1s2, electrons in the outermost shell that determine the chemical properties of the element.

Unabbreviated electronic configuration of neutral Helium

Complete ground state electronic configuration for the Helium atom, Unabbreviated electronic configuration

1s2

Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.

  • As per the Aufbau principle the electrons will occupy the orbitals having lower energies before occupying higher energy orbitals. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
  • The Pauli exclusion principle states that a maximum of two electrons, each having opposite spins, can fit in an orbital.
  • Hund's rule states that every orbital in a given subshell is singly occupied by electrons before a second electron is filled in an orbital.
  • Electron configuration of Helium
    Atomic Structure of Helium

    Helium atomic radius is 31 pm, while it's covalent radius is 32 pm.

    Atomic Radius Calculated

    31 pm (0.31 Å)

    Atomic Radius Empirical

    120 pm (1.2 Å)

    Atomic Volume22.4136 cm3/mol
    Covalent Radius32 pm (0.32 Å)
    Van der Waals Radius140 pm
    Neutron Cross Section0.007
    Neutron Mass Absorption 0.00001

    Atomic Spectrum of Helium

    Atomic Spectrum of Helium | SchoolMyKids

    Helium Chemical Properties: Helium Ionization Energies and electron affinity

    The electron affinity of Helium is 0 kJ/mol.

    Valence0
    Electronegativity-
    ElectronAffinity0 kJ/mol

    Ionization Energy of Helium

    Refer to table below for Ionization energies of Helium

    Ionization energy numberEnthalpy - kJ/mol
    1st2372.3
    2nd5250.5

    Helium Physical Properties

    Refer to below table for Helium Physical Properties

    Density0.0001785 g/cm3
    Molar Volume22.4136 cm3/mol

    Elastic Properties

    Young Modulus-
    Shear Modulus-
    Bulk Modulus -
    Poisson Ratio-

    Hardness of Helium - Tests to Measure of Hardness of Element

    Mohs Hardness-
    Vickers Hardness-
    Brinell Hardness-

    Helium Electrical Properties

    Helium is Conductor of electricity. Refer to table below for the Electrical properties ofHelium

    Electrical Conductivity-
    Resistivity-
    Superconducting Point-

    Helium Heat and Conduction Properties

    Thermal Conductivity0.1513 W/(m K)
    Thermal Expansion-

    Helium Magnetic Properties

    Magnetic TypeDiamagnetic
    Curie Point-
    Mass Magnetic Susceptibility-5.9e-9 m3/kg
    Molar Magnetic Susceptibility-2.36e-11 m3/mol
    Volume Magnetic Susceptibility-1.05e-9

    Optical Properties of Helium

    Refractive Index1.000035

    Acoustic Properties of Helium

    Speed of Sound970 m/s

    Helium Thermal Properties - Enthalpies and thermodynamics

    Refer to table below for Thermal properties of Helium

    Melting Point0 K (-273.15°C, -459.66999999999996 °F)
    Boiling Point4.22 K (-268.93°C, -452.0739999999999 °F)
    Critical Temperature5.19 K
    Superconducting Point-

    Enthalpies of Helium

    Heat of Fusion0.02 kJ/mol
    Heat of Vaporization0.083 kJ/mol
    Heat of Combustion-

    Helium Isotopes - Nuclear Properties of Helium

    Helium has 8 isotopes, with between 3 and 10 nucleons. Helium has 2 stable naturally occuring isotopes.

    Isotopes of Helium - Naturally occurring stable Isotopes: 3He, 4He.

    IsotopeZNIsotope Mass% AbundanceT halfDecay Mode
    3He2130.000137%StableN/A
    4He22499.999863%Stable
    5He235Synthetic
    6He246Synthetic
    7He257Synthetic
    8He268Synthetic
    9He279Synthetic
    10He2810Synthetic

    Regulatory and Health - Health and Safety Parameters and Guidelines

    Database Search

    List of unique identifiers to search the element in various chemical registry databases

    DatabaseIdentifier number
    CAS Number - Chemical Abstracts Service (CAS)CAS7440-59-7
    RTECS NumberRTECSMH6520000
    CID Number CID23987
    Gmelin Number-
    NSC Number-

    Compare Helium with other elements

    Compare Helium with all Group 18 elements

    Compare Helium with all Period 1 elements

    Compare Helium with all Noble Gas elements