Hílíọ̀mù, Hélíọ̀m, tabi Helium (pípè /ˈhiːliəmu/, HEE-lee-əm) ni ẹ́límẹ̀ntì kẹ́míkà tó ní nọ́mbà átọ́mù 2 àti iwuwo atomu to je 4.002602, àmì ìdámọ̀ rẹ̀ ni He. O je efuufu oniatomukan, alaigbera, aláìláwọ̀, alailoorun, alainitowo, ati alailewu to siwaju ẹgbẹ́ ẹ̀fúùfù abíire ninu tabili asiko. Awon ojuami ìhó àti ìyọ́ rẹ̀ je awon ti won kerejulo larin awon ẹ́límẹ̀ntì, o si wa pere gege bi efuufu ayafi nigba to ba wa nipo lounloun. Leyin hydrogen, ohun ni elimenti keji to pojulo ni agbalaaye, o si je bi 24% gbogbo akojo elimenti ninu galaksi wa.
Hílíọ̀mù, 2He |
Hílíọ̀mù |
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Pípè | /ˈhiːliəm/ (HEE-lee-əm) |
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Ìhànsójú | ẹ̀fúùfù aláìláwọ̀, yíò tan àwọ̀ ọsàn-pupa tó bá wà nínú pápá ìtanna ìtiná gíga |
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Ìwúwo átọ̀mù Ar, std(He) | 4.002602(2)[1] |
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Hílíọ̀mù ní orí tábìlì àyè |
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Nọ́mbà átọ̀mù (Z) | 2 |
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Ẹgbẹ́ | group 18 (noble gases) |
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Àyè | àyè 1 |
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Àdìpọ̀ | Àdìpọ̀-s |
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Ẹ̀ka ẹ́límẹ́ntì | Ẹ̀fúùfù abíire |
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Ìtò ẹ̀lẹ́ktrọ́nù | 1s2 |
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Iye ẹ̀lẹ́ktrọ́nù lórí ìpele kọ̀ọ̀kan | 2 |
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Àwọn ohun ìní ara |
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Ìfarahàn at STP | ẹ̀fúùfù |
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Ìgbà ìyọ́ | (at 2.5 MPa) 0.95 K (−272.20 °C, −457.96 °F) |
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Ígbà ìhó | 4.22 K (−268.93 °C, −452.07 °F) |
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Kíki (at STP) | 0.1786 g/L |
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when liquid (at m.p.) | 0.145 g/cm3 |
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when liquid (at b.p.) | 0.125 g/cm3 |
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Critical point | 5.19 K, 0.227 MPa |
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Heat of fusion | 0.0138 kJ/mol |
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Heat of | 0.0829 kJ/mol |
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Molar heat capacity | 5R/2 = 20.786 J/(mol·K) |
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pressure (defined by ITS-90)
P (Pa)
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1
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10
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100
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1 k
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10 k
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100 k
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at T (K)
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1.23
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1.67
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2.48
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4.21
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Atomic properties |
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Oxidation states | 0 |
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Electronegativity | Pauling scale: no data |
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Covalent radius | 28 pm |
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Van der Waals radius | 140 pm |
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Spectral lines of hílíọ̀mù |
Other properties |
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Natural occurrence | primordial |
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Crystal structure | hexagonal close-packed (hcp) |
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Speed of sound | 972 m/s |
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Thermal conductivity | 0.1513 W/(m·K) |
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Magnetic ordering | diamagnetic[2] |
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CAS Number | 7440-59-7 |
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History |
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Discovery | Pierre Janssen, Norman Lockyer (1868) |
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First isolation | William Ramsay, Per Teodor Cleve, Abraham Langlet (1895) |
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Main isotopes of hílíọ̀mù |
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- Atmospheric value, abundance may differ elsewhere.
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Àdàkọ:Category-inline | references |