Selenium,  ₃₄Se

ngoi-kôn
black, red, and gray (not pictured) allotropes
Kî-pún sin-sit
Miàng, fù-ho	Selenium, Se
ngoi-hìn	black, red, and gray (not pictured) allotropes
Selenium chhai chû-khì-péu ke vi-chi
S ↑ Se ↓ Te phî ← Selenium → chhiu
ngièn-chṳ́ sì-sú	34
ngièn-chṳ́-liòng (±)	78.971(8)[1]
ngièn-su lui-phe̍t	tô-ngièn-chṳ́ fî-kîm-su̍k, sometimes considered a metalloid
Chhu̍k, fûn-khî	16 chhu̍k, p-block
chû-khì	period 4
thien-chṳ́ phài-lie̍t	[Ar] 3d10 4s2 4p4
per shell	2, 8, 18, 6
vu̍t-lî sin-chṳt
Siông	ku-thí
yùng-tiám	494 K ​(221 °C, ​430 °F)
pui-tiám	958 K ​(685 °C, ​1265 °F)
Me̍t-thu near Sit-vûn	gray: 4.81 g·cm−3 alpha: 4.39 g·cm−3 vitreous: 4.28 g·cm−3
3.99 g·cm−3
lìm-kie-tiám	1766 K, 27.2 MPa
Yùng-fa-ngie̍t	gray: 6.69 kJ·mol−1
Chîn-fat-ngie̍t	95.48 kJ·mol−1
Ngie̍t-yùng-liong	25.363 J·mol−1·K−1
chîn-hi-ap P (Pa) 1 10 100 1 k 10 k 100 k chhai T (K) 500 552 617 704 813 958
Ngièn-chṳ́ sin-chṳt
Yông-fa-su	6, 5, 4, 3, 2, 1,[2] −1, −2 ​(a strongly acidic oxide)
Thien-fu-sin	Pauling scale: 2.55
Thien-lì-nèn	1st: 941.0 kJ·mol−1 2nd: 2045 kJ·mol−1 3rd: 2973.7 kJ·mol−1
Ngièn-chṳ́ pan-kang	empirical: 120 pm
Khiung-ka pan-kang	120±4 pm
Van der Waals pan-kang	190 pm
Miscellanea
Chîn-thí keu-chho	​hexagonal
Sâng-suk thin rod	3350 m·s−1 (at 20 °C)
Ngie̍t-phàng-chong	amorphous: 37 µm·m−1·K−1 (at 25 °C)
Ngie̍t-chhòn-thô-li̍t	amorphous: 0.519 W·m−1·K−1
Chhṳ̀-sin	diamagnetic[3]
Young's modulus	10 GPa
Shear modulus	3.7 GPa
Bulk modulus	8.3 GPa
Poisson ratio	0.33
Mohs hardness	2.0
Brinell hardness	736 MPa
CAS Registry Number	7782-49-2
Le̍k-sú
Hí-miàng	after Selene, Greek goddess of the moon
Hoat-kiàn kap siōng chá ê tông-ūi-sò͘	Jöns Jakob Berzelius and Johann Gottlieb Gahn (1817)
Chui vún-thin ke thùng-vi-su
Chú vùn-chông: Selenium ke thùng-vi-su
iso NA half-life DM DE (MeV) DP 72Se syn 8.4 d ε – 72As γ 0.046 – 74Se 0.87% – (β+β+) 1.2094 74Ge 75Se syn 119.779 d ε – 75As γ 0.264, 0.136, 0.279 – 76Se 9.36% 76Se is stable with 42 neutrons 77Se 7.63% 77Se is stable with 43 neutrons 78Se 23.78% 78Se is stable with 44 neutrons 79Se trace 3.27×105 y β− 0.151 79Br 80Se 49.61% – (β−β−) 0.1339 80Kr 82Se 8.73% 1.08×1020 y β−β− 2.995 82Kr
Decay modes in parentheses are predicted, but have not yet been observed

Selenium (Hon-ngî: 硒 xī) he yit-chúng fa-ho̍k ngièn-su, fa-ho̍k fù-ho vì Se, ngièn-chṳ́ su-muk he 34.