
Helium (He) is a chemical element of the periodic table, located in the group 18 and the period 1, and is having the atomic number 2. It is a colorless, odorless, tasteless, non-toxic gas, whose name comes from the Greek word “helios”, which means sun. It is the first element in the noble gas group. It is the second lightest element, after the hydrogen element.
group | ⇨ | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
period | ⇩ | ||||||||||||||||||
1 | 1 H ![]() Hydrogen |
2 He ![]() Helium |
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2 | 3 Li ![]() Lithium |
4 Be ![]() Beryllium |
5 B ![]() Boron |
6 C ![]() Carbon |
7 N ![]() Nitrogen |
8 O ![]() Oxygen |
9 F ![]() Fluorine |
10 Ne ![]() Neon |
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3 | 11 Na ![]() Sodium |
12 Mg ![]() Magnesium |
13 Al ![]() Aluminium |
14 Si ![]() Silicon |
15 P ![]() Phosphorus |
16 S ![]() Sulfur |
17 Cl ![]() Chlorine |
18 Ar ![]() Argon |
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4 | 19 K ![]() Potassium |
20 Ca ![]() Calcium |
21 Sc ![]() Scandium |
22 Ti ![]() Titanium |
23 V ![]() Vanadium |
24 Cr ![]() Chromium |
25 Mn ![]() Manganese |
26 Fe ![]() Iron |
27 Co ![]() Cobalt |
28 Ni ![]() Nickel |
29 Cu ![]() Copper |
30 Zn ![]() Zinc |
31 Ga ![]() Gallium |
32 Ge ![]() Germanium |
33 As ![]() Arsenic |
34 Se ![]() Selenium |
35 Br ![]() Bromine |
36 Kr ![]() Krypton |
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5 | 37 Rb ![]() Rubidium |
38 Sr ![]() Strontium |
39 Y ![]() Yttrium |
40 Zr ![]() Zirconium |
41 Nb ![]() Niobium |
42 Mo ![]() Molybdenum |
43 Tc ![]() Technetium |
44 Ru ![]() Ruthenium |
45 Rh ![]() Rhodium |
46 Pd ![]() Palladium |
47 Ag ![]() Silver |
48 Cd ![]() Cadmium |
49 In ![]() Indium |
50 Sn ![]() Tin |
51 Sb ![]() Antimony |
52 Te ![]() Tellurium |
53 I ![]() Iodine |
54 Xe ![]() Xenon |
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6 | 55 Cs ![]() Caesium |
56 Ba ![]() Barium |
72 Hf ![]() Hafnium |
73 Ta ![]() Tantalum |
74 W ![]() Tungsten |
75 Re ![]() Rhenium |
76 Os ![]() Osmium |
77 Ir ![]() Iridium |
78 Pt ![]() Platinum |
79 Au ![]() Gold |
80 Hg ![]() Mercury |
81 Tl ![]() Thallium |
82 Pb ![]() Lead |
83 Bi ![]() Bismuth |
84 Po ![]() Polonium |
85 At ![]() Astatine |
86 Rn ![]() Radon |
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7 | 87 Fr ![]() Francium |
88 Ra ![]() Radium |
104 Rf ![]() Rutherfordium |
105 Db ![]() Dubnium |
106 Sg ![]() Seaborgium |
107 Bh ![]() Bohrium |
108 Hs ![]() Hassium |
109 Mt ![]() Meitnerium |
110 Ds ![]() Darmstadtium |
111 Rg ![]() Roentgenium |
112 Cn ![]() Copernicium |
113 Nh ![]() Nihonium |
114 Fl ![]() Flerovium |
115 Mc ![]() Moscovium |
116 Lv ![]() Livermorium |
117 Ts ![]() Tennessine |
118 Og ![]() Oganesson |
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57 La ![]() Lanthanum |
58 Ce ![]() Cerium |
59 Pr ![]() Praseodymium |
60 Nd ![]() Neodymium |
61 Pm ![]() Promethium |
62 Sm ![]() Samarium |
63 Eu ![]() Europium |
64 Gd ![]() Gadolinium |
65 Tb ![]() Terbium |
66 Dy ![]() Dysprosium |
67 Ho ![]() Holmium |
68 Er ![]() Erbium |
69 Tm ![]() Thulium |
70 Yb ![]() Ytterbium |
71 Lu ![]() Lutetium |
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89 Ac ![]() Actinium |
90 Th ![]() Thorium |
91 Pa ![]() Protactinium |
92 U ![]() Uranium |
93 Np ![]() Neptunium |
94 Pu ![]() Plutonium |
95 Am ![]() Americium |
96 Cm ![]() Curium |
97 Bk ![]() Berkelium |
98 Cf ![]() Californium |
99 Es ![]() Einsteinium |
100 Fm ![]() Fermium |
101 Md ![]() Mendelevium |
102 No ![]() Nobelium |
103 Lr ![]() Lawrencium |
– s block |
Helium Element Information
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Origin of name | Greek word “helios” (which means sun) |
Symbol | He |
Atomic number (Z) | 2 |
Atomic mass | 4.002602 u |
Block | s-block |
Group | 18 |
Period | 1 |
Classification | Noble gas |
Covalent radius | 28 pm |
Van der Waals radius | 140 pm |
Melting point | -272.20 ℃, -457.96 ℉, 0.95 K |
Boiling point | -268.928 ℃, -452.070 ℉, 4.222 K |
Electron configuration | 1s2 |
Electrons per shell | 2 |
Learn how to draw: Helium Bohr Model | |
Crystal structure | Hexagonal close-packed (hcp) |
Phase at r.t | Gas |
Density near r.t | 0.1786 g/L |
Main isotopes | Helium-3, Helium-4 |
Natural occurrence | Primordial |
Oxidation state | 0 |
Protons Neutrons Electrons |
2 2 2 |
Learn how to find: Helium Protons Neutrons Electrons | |
Valence electrons | 2 |
Learn how to find: Helium Valence Electrons | |
CAS number | 7440-59-7 |
Discovered by | Pierre Janssen Norman Lockyer in 1868 |
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