Pengguna:Agung.karjono/Bak pasir/Timbal(II) nitrat: Perbedaan antara revisi
Konten dihapus Konten ditambahkan
Baris 15:
Belerang adalah [[Mineral (nutrisi)|unsur penting]] untuk semua kehidupan, tetapi hampir selalu dalam bentuk senyawa [[Senyawa organosulfur|organosulfur]] atau sulfida logam. Tiga [[asam amino]] ([[Sisteina|sistein]], {{Ill|sistin|en|cystine}}, dan [[Metionina|metionin]]) dan dua [[vitamin]] ([[biotin]] dan [[Tiamina|tiamin]]) adalah senyawa organosulfur. Banyak [[Kofaktor (biokimia)|kofaktor]] juga mengandung belerang, termasuk [[glutation]], {{Ill|thioredoksin|en|thioredoxin}}, dan {{Ill|Protein besi–belerang|en|iron–sulfur proteins}}. [[Disulfida]], ikatan S–S, memberi kekuatan mekanis dan ketaklarutan protein [[keratin]], yang ditemukan di kulit luar, rambut, dan bulu. Belerang adalah salah satu unsur kimia inti yang dibutuhkan untuk fungsi [[biokimia]] dan [[Makronutrien|unsur hara makro]] bagi semua organisme hidup.
==
[[File:Burning-sulfur.png|thumb|left|
===
Sulfur forms several polyatomic molecules. The best-known allotrope is [[octasulfur]], cyclo-S<sub>8</sub>. The [[point group]] of cyclo-S<sub>8</sub> is D<sub>4d</sub> and its dipole moment is 0 D. Octasulfur is a soft, bright-yellow solid that is odorless, but impure samples have an odor similar to that of [[match]]es.<ref>A strong odor called "smell of sulfur" actually is given off by several sulfur compounds, such as [[hydrogen sulfide]] and [[organosulfur]] compounds.</ref> It melts at {{convert|115.21|C}}, boils at {{convert|444.6|C}} and sublimes easily.<ref name="Greenwd" /> At {{convert|95.2|C}}, below its melting temperature, cyclo-octasulfur changes from α-octasulfur to the β-[[polymorphism (materials science)|polymorph]].<ref name= ===Chemical properties===
|