Helium

2
He
Kumpulan
18
Kala
1
Blok
s
Proton
Elektron
Neutron
2
2
2
Ciri-Ciri Am
Nombor atom
2
Berat atom
4.002602
Nombor jisim
4
Kategori
Gas adi
Warna
Tidak berwarna
Radioaktif
Tidak
Daripada perkataan Yunani helios, matahari
Struktur hablur
Pusat Wajah Kubik
Sejarah
French astronomer Jules Janssen obtained the first evidence of helium during the solar eclipse of 1868.

Norman Lockyer and Edward Frankland suggested the name helium for the new element.

In 1895, Sir William Ramsay discovered helium in the uranium mineral cleveite.

It was independently discovered in cleveite by Per Teodor Cleve and Abraham Langlet.
Bilangan elektron per petala
2
Konfigurasi elektron
1s2
He
Unlike any other element, helium will remain liquid down to absolute zero at normal pressures
Ciri-Ciri Fizikal
Fasa
Gas
Ketumpatan
0.0001785 g/cm3
Takat lebur
0.95 K | -272.2 °C | -457.96 °F
Takat didih
4.22 K | -268.93 °C | -452.07 °F
Haba pelakuran
0.02 kJ/mol
Haba pengewapan
0.083 kJ/mol
Muatan haba molar
5.193 J/g·K
Banyak pada kerak bumi
5.5×10-7%
Banyak pada alam semesta
23%
Vial
Kredit imej: Images-of-elements
Vial of glowing ultrapure helium
Nombor CAS
7440-59-7
PubChem CID Number
23987
Ciri-Ciri Atom
Jejari atom
31 pm
Jejari kovalen
28 pm
Keelektronegatifan
-
Kebolehan mengion
24.5874 eV
Isipadu atom
27.2 cm3/mol
Daya pengaliran terma
0.00152 W/cm·K
Keadaan pengoksidaan
0
Aplikasi
Helium is used as a protective gas in growing silicon and germanium crystals, in titanium and zirconium production, and in gas chromatography.

Helium at low temperatures is used in cryogenics.

Helium is used for filling balloons and for pressurizing liquid fuel rockets.

Helium is used as a shielding gas in arc welding processes.
Helium is not known to be toxic
Isotop
Isotop stabil
3He, 4He
Isotop tidak stabil
5He, 6He, 7He, 8He, 9He, 10He