从软锰矿到锰同位素：锰元素的发现及其概念的发展

1771年，瑞典化学家托伯恩·伯格曼明确提出软锰矿中含有新元素的假说，并将之初步命名为manganese(锰)。1774年，瑞典矿物学家甘恩首次制取出锰单质，锰元素假说得以验证。同年，瑞典化学家舍勒对锰单质的性质进行了表征，并确认manganese(锰)一词为该元素命名，锰元素的概念正式形成。同位素化学兴起后，1923年至今共发现25种锰的同位素，锰元素被明确定义为质子数为25的所有原子的总称。锰元素的发现浓缩了19世纪初系统分析法形成以前早期分析化学的发展，其概念的演变渗透出系统分析法的形成以及同位素化学的兴起，在定性到定量的研究过程中体现了科学思想和方法的进步。     

钛元素的发现及其概念发展

1791年,英国矿物学家格雷戈尔发现钛矿石并意识到一种新元素的存在。至1795年,普鲁士化学家克拉普罗特进一步预言了该元素,并将之正式命名为钛(Titanium)。1910,美国化学家亨特制取了纯净的钛单质,钛元素的概念正式形成。20世纪20年代以后,钛同位素的发现使人们对钛元素概念有了新认识,并逐渐形成现代钛元素概念。钛元素概念的发展使人们在科学认知上发生了转变,促进了化学元素观的演进。     

从简单土质物质到现代化学元素：钙元素的发现及其概念的发展

18世纪末,法国化学家拉瓦锡预言石灰等土质不是简单物质。19世纪初,英国化学家戴维利用电化学技术从石灰中制得一种新的金属,并将其命名为“钙”(calcium),钙元素概念初步形成。随后,原子论的提出与钙原子量的测定使钙元素概念得到发展。到了20世纪,钙元素同位素的发现使人们对钙元素概念有了新的认识。总之,钙元素概念的发展史不仅是元素概念的发展史,也是科学思想、科学方法的演变史。     

含氯消毒剂次氯酸钠发展史*

1774年,瑞典化学家舍勒(C.W.Scheele,1742-1786)在加热黑色的二氧化锰与盐酸的混合物时,产生了一种烟雾,按照当时流行的说法将这种气体命名为“脱脂化盐酸”。直到1810年,英国科学家戴维(Humphry Davy,1778-1829)正式提出“氯”这种元素的存在,并将这种单质命名为“氯气”。     

镉元素的发现及其概念的发展

通过对镉元素概念发展历程的考证分析可知,19世纪初,随着科学思想和化学分析方法的发展,德国化学家斯特罗迈耶首次通过药物分析制取并命名镉单质。至1826年,瑞典化学家贝采利乌斯首次测定镉原子量,赋予镉元素新的含义。镉原子量测定以及元素周期表形成,使镉元素的概念和镉原子结合起来。1924年,英国化学家阿斯顿通过质谱仪发现了镉同位素,从而形成了现代的镉元素概念。总之,随着科学思想和方法的不断发展,镉元素概念的内涵也在不断发展变化。     

金属材料分析方法的选择和施行第五讲金属材料中钨的测定

1概述1.1钨的性质1781年社勒发现了三氧化钨,从而认识了元素钨。在地球上,钨仅占岩石圈的1.6×10-1%。因此被认为是一种稀有元素。钨的主要矿物有白钨矿(CaWO4)和黑钨矿(钨酸铁FeWO4和钨酸锰MnWO4的混合晶体)。     

锆元素概念的形成和发展

1789年,普鲁士分析化学家克拉普罗特提出黄锆石中含有一种新土质,并将其命名为“锆土”,锆元素假说正式形成。随后,锆的原子重量的测定以及锆元素在元素表中位置的确定,促进了锆元素假说的发展。1914年,荷兰工程师勒利和汉布格首次制得纯度较高的金属锆,这使得锆元素假说得以证实,锆元素概念正式形成。从1924年至2020年,锆同位素的发现使人们对锆元素有了新认识,促使了现代锆元素概念的形成。锆元素概念的形成和发展的过程既是元素的发现史,也是化学思想和化学方法的演进史。     

氢键概念的形成和发展

1902年,瑞士化学家维尔纳对氯化铵结构的解释为氢键概念的形成奠定了基础。1920年,美国化学家拉提麦尔和罗德布什首先认识了水中的氢键：2个八隅体所持的氢核构成的“弱键(weak bond)”。1928年,美国化学家鲍林在解释[FHF]^-的结构时首次使用“氢键(hydrogen bond)”一词,但并未对氢键的概念进行明确定义。1939年,鲍林在《化学键的本质》中明确提出了氢键的概念,并解释了氢键的性质,自此,氢键的概念正式形成。近年来,科学家经过深入研究发现了氢键的新类型：π型氢键、双氢键、金属氢键和单电子氢键。随着科学思想和科学技术的发展,关于氢键的认识也会越来越深入。     

从铂矿残渣到钌同位素：钌元素的发现及其概念发展

从1828年到1931年，经过化学家的百年探索，现代钌元素的概念逐渐形成。主要分为3个阶段：从钌铂矿残渣分离出不纯的钌元素样品，钌单质的成功制备以及钌同位素的发现。在钌元素概念形成和发展的过程中，创造性的直觉思维发挥了重要作用，严谨求实的科学态度和批判质疑的科学精神也功不可没。     

氩元素概念的形成和发展与化学思想的演进

19世纪末英国化学家瑞利和拉姆塞发现了氩元素，引发了“惰性气体”的发现，开辟了周期表中的零族元素；20世纪20年代氩元素同位素的发现使人们对氩元素的概念有了新认识；21世纪初，氩化合物的发现使人们对氩的“惰性”有了全新的认识，改称氩为稀有气体元素。总之，氩元素概念的形成和发展对于元素周期律的完善和发展，以及人们对原子结构和化学键理论的认识都起到了极为重要的桥梁作用。     

“能干而低调”的钨元素

较为详细地介绍了钨元素的发现历程,钨金属与合金、含钨杂多配合物、氧化钨、碳化钨、钨硫族化合物和含有W-W四重键的化合物的应用。     

重量法测定高锡钨精矿中的钨

为消除重量法测定钨精矿中钨时锡的干扰,在溶解过程中用氢溴酸反复冒烟进行消除,利用ICP–OES法测定残渣和滤液中剩余钨量,再与传统重量法相结合进行钨的定量测定。结果表明,该方法的检出限为0.01μg/m L,测定结果的相对标准偏差为3.53%~5.26%(n=5),加标回收率为98.78%~100.93%。该分析方法不仅能够消除锡的干扰,而且可以相对快速得到稳定可靠的结果。     

Fabrication of Two‐Dimensional Lateral Heterostructures of WS2/WO3⋅H2O Through Selective Oxidation of Monolayer WS2

Two‐dimensional (2D) lateral heterostructures have emerged as a hot topic in the fast evolving field of advanced functional materials , but their fabrication is challenging. The layer‐structured WS₂ was theoretically demonstrated to be inert to oxidation except for the monolayer, which can be selectively oxidized owing to the simultaneous interaction of oxygen with both sides. Combined with the theoretical calculations, a new method was developed for the successful construction of 2D lateral heterostructures of WS₂/WO₃?H₂O in an ambient environment, based on a simple liquid‐phase solution exfoliation. These lateral heterostructures of WS₂/WO₃?H₂O have interesting properties, as indicated by enhanced photocatalytic activity toward the degradation of methyl orange (MO).     

ICP–OES法测定八氧化三铀中杂质元素钨

以ICP–OES法测定八氧化三铀中杂质元素钨。采用浓HNO3–浓HCl、浓HNO–HF、3 mol/L HNO3三步酸溶方案,利用CL–TBP萃淋树脂将铀基体分离,淋洗液基质为3 mol/L HNO3,淋洗液流速为1 mL/min。弃去最初2 mL死体积淋洗液后接收10 mL,分离回收率平均值为95.93%,线性方程为y=539.71x+16.6,相关系数r2=0.999 7,4水平样品测定结果的相对标准偏差为0.39%~3.12%(n=6)。用该方法对标准物质进行测定,测定结果在参考值范围内。     

混合价钨氧化物的制备及其性质研究

Precursors were synthesized with hydrazine oxalic acid and tungstic acid in different ratios and a series of tungsten oxides， O/W ratios from 2.90 to 2.30，were obtained by thermal decomposition from the precursors under nitrogen atmosphere at 640～760℃. This kind of tungsten oxides were found to belong to mixed valence compounds which have some special electrical properties. The experimental result indicated that the electrical conductivity of this tungsten oxide has a close relation with its O/W ratio and reach the maximum at WO_2.50. Seclecting WO_2.50 as an example， its conductivity was measured at different temperatures from -197 ℃ to -2.5 ℃ and it was found that the mixed valence tungsten oxide as conductor belongs to the class of metal ones. Owing to their relatively high electrical conductivity and stability in air， mixed valence tungsten oxide shows some potential use in polymer products as additives.     

Electrochemical approaches to generation of phosphinidene complexes of tungsten pentacarbonyl

An alternative approach to synthesis of electrophilic terminal phosphinidene complexes of tungsten pentacarbonyl with various substituents at the phosphorus atom has been developed. The approach is based on the reaction of the electrochemically generated tungsten pentacarbonyl ion with trivalent phosphorus acyl chlorides. Electrochemical reduction of ethyldichlorophosphines in the presence of α-diimines is a one-step process that forms 1,3,2-diazaphospholenes containing an exocyclic P-C bond.     

Electrochemical Detection of Nitrite Using an Asymmetrically Substituted Cobalt Phthalocyanine Conjugated to Metal Tungstate Nanoparticles

This paper explores the synthesis and characterisation of an asymmetrical Co phthalocyanine (CoPc), and its covalent linking to two tungsten nanoparticles: bismuth tungsten oxide (Bi₂WO₆) and nickel tungsten oxide (NiWO₄). The nanoparticles were also mixed with the CoPc. The CoPc, nanoparticles and their respective conjugates were used as electrocatalysts in the electrochemical detection of nitrite. The electrocatalysts studied in this work had sensitivities ranging from 3–133 μA/mM while the limits of detection (LoDs) ranged between 0.063 μM and 1.7 μM. Bi₂WO₆ and its conjugate exhibited better LoD than corresponding NiWO₄ and conjugate.     

Multi-element trace analysis of tungsten

Investigations carried out in order to determine traces of 25 elements in tungsten in the lower g/g range are reported on. Atomic absorption spectrometry and plasma atomic emission spectrometry as well as solution photometry and activation analysis were the main techniques used.     

Gasochromic Effect in Platinum-Doped Tungsten Trioxide Films Prepared by the Sol-Gel Method

Tungsten oxide doped by a complex of platinum exhibits a gasochromic effect. A reversible coloration is observed on successive exposure to hydrogen and air. The films were prepared by the sol-gel method at room temperature. They showed strong darkening (blue color) on exposure to hydrogen and were bleached completely when exposed to air. The proccess has been reproduced completely hundreds of times without any losses. The cycling of the coloration was obtained from UV-Vis spectra and the mechanism deduced from both visible and Fourier transform infrared (FTIR) spectra. Colorimetric properties of the gasochromic films were expressed in color space chromaticity diagram.     

介稳态氧化钨超微粉体的水热合成与光致变色性质研究

Under hydrothermal conditions, the superfine powders of cubic pyrochlore-type of tungsten oxide and hexagonal tungsten bronze were obtained by using Na₂WO₄·2H₂O as the starting material. The products were characterized by XRD, TG, IR, UV and EPMA, respectively. The effects of the pH value, the acid concentration, reaction temperature and time on the structure and particle size of products were investigated in detail. The conditions for the preparation of superfine powders of tungsten oxide were optimized. The pH 2.5～4.5 of the reaction system led to the formation of a pyrochlore phase and pH 0.5～2.0 gave the hexagonal tungsten bronze structure. The photochromism property of the hexagonal tungsten bronze was studied. The results show that pyrochlore and bronze phases are decomposed at 300 ℃ and 450 ℃, respectively. With the increasing of temperature, the structure of the two oxides changes. The pyrochlore-type powder changes completely into triclinic Na₂W₄O₁₃ around 500 ℃, while the bronze phase into a mixture of Na₂W₆O₁₉ and triclinic WO₃ at 550 ℃. The powder of the hexagonal tungsten bronze showed better photochromism property.