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Hace 17 horas · Lawrencium is a synthetic chemical element; it has symbol Lr (formerly Lw) and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranic element and the last member of the actinide series.
- silvery (predicted)
- [266]
- 103
Hace 17 horas · Methane is a tetrahedral molecule with four equivalent C–H bonds. Its electronic structure is described by four bonding molecular orbitals (MOs) resulting from the overlap of the valence orbitals on C and H. The lowest-energy MO is the result of the overlap of the 2s orbital on carbon with the in-phase combination of the 1s orbitals on the ...
- CH₄
- 16.043 g·mol−1
- −182.456 °C (−296.421 °F; 90.694 K)
- 22.7 mg/L
Hace 17 horas · Chemistry. Nicotine is a hygroscopic, colorless to yellow-brown, oily liquid, that is readily soluble in alcohol, ether or light petroleum. It is miscible with water in its neutral amine base form between 60 °C and 210 °C. It is a dibasic nitrogenous base, having K b1 =1×10 −6, K b2 =1×10 −11. [160]
Hace 17 horas · Polonium is a radioactive element that exists in two metallic allotropes. The alpha form is the only known example of a simple cubic crystal structure in a single atom basis at STP ( space group Pm 3 m, no. 221). The unit cell has an edge length of 335.2 picometers; the beta form is rhombohedral.
- α, β
- [209]
- silvery
Hace 17 horas · 1923 - Roscoe Dickinson and Albert Raymond, and independently, H.J. Gonell and Hermann Mark, first showed that an organic molecule, specifically hexamethylenetetramine, could be characterized by x-ray crystallography. [64] [65] 1923 - William H. Bragg and Reginald E. Gibbs elucidated the structure of quartz.
Hace 17 horas · Infobox references. Serotonin ( / ˌsɛrəˈtoʊnɪn, ˌsɪərə -/) [6] [7] [8] or 5-hydroxytryptamine ( 5-HT) is a monoamine neurotransmitter. Its biological function is complex, touching on diverse functions including mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction. [9]
Hace 17 horas · Up to a temperature of 0.01 °C, the triple point of water, water normally exists as ice, except for supercooled water, for which one data point is tabulated here. At the triple point, ice can exist together with both liquid water and vapor. At higher temperatures, the data are for water vapor only.
