溴元素发现史上的成功和遗憾及其历史意义

1826年,法国青年化学家巴拉尔宣布发现了溴元素。然而,同时期的德国化学家李比希、洛威等人面对相似的实验现象与溴元素的发现失之交臂。溴元素的发现使卤族基本成型,增强了科学家验证氟元素假说的信心,并促进了元素周期律的发现。同时,溴元素的发现过程彰显了批判精神和直觉思维对于科学发现的重要作用,说明了科学态度是从事科学研究的必备素养。     

有关和平利用原子能的若干化学问题(上)

大家知道,原子堆一方面可用于生产量较多的放射性同位素;另一方面它也能提供强大的中子源作中子物理与中子衍射等研究之用。回旋加速器可生产少量放射性同位素(特别是半衰期很短的)供研究用,但它的主要的用途是加速带电荷的粒子,并用它们来轰击原子核以产生核反应。物理学家通过核反应所引起的变化的观察,可以了解复杂的核结构问题。虽然,在上述一些研究中物理学家所起的作用最重要;但是,和平利用原子能的总计划的完成,同时需要化学家,数学家,冶金学家,工程师,生物学家,农艺学家与医学家等多方面的配合与共同努力。很早以前,化学家便在原     

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。     

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。     

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。     

钨元素的发现及其概念的发展

1781年,瑞典化学家舍勒在白钨矿中发现了钨酸,预测其中一定含有一种新金属元素,并将其命名为钨(Tungsten)。1783年,西班牙化学家德鲁亚尔兄弟从黑钨矿中成功提取出了舍勒所说的新金属单质,将其命名为钨(Wolfram)。1803年,英国化学家道尔顿原子论的提出,赋予钨元素新的含义:具有一定质量的钨原子。1930年以后,钨同位素的发现使人们对钨元素有了新认识,并逐渐形成了现代钨元素的概念。关于钨元素的认识经历了从假说到客观存在、从定性到定量、从宏观到微观的发展历程。钨元素概念的演变体现了科学思想和科学方法的进步。     

电负性研究的新进展——1.桑德逊电负性标度及其对经典电负性概念的改进

1932年鲍林(Pauling)首次提出元素电负性概念,经化学家和物理学家长期运用与研究,其定义、计算方法、应用范围和理论根据等方面都得到了广泛发展与许多成功改进。     

迈向元素周期律的第一人:约翰·沃尔夫冈·杜布莱纳

德国化学家约翰·沃尔夫冈·杜布莱纳于1829年提出元素三组律，是探索元素性质与原子量之间关系的第一人，开创了元素周期律研究的先河，同时也在化学的许多其他领域做出了重大贡献。2019年是国际化学元素周期表年，同时也是杜布莱纳逝世170周年，谨以此文纪念这位伟大的学者。     

Mendeleyev revisited

Despite the periodic table having been discovered by chemists half a century before the discovery of electronic structure, modern designs are invariably based on physicists’ definition of periods. This table is a chemists’ table, reverting to the phenomenal periods that led to the table’s discovery. In doing so, the position of hydrogen is clarified.

     

The Active Sites in Manganese-Containing Metalloproteins and Inorganic Model Complexes

Manganese is an essential trace element, forming the active sites of a number of metalloproteins. Several metalloproteins contain two or more manganese ions per subunit. The structural properties of these enzymes and the experimental evidence for their proposed structures are described. Parallel to the efforts of biochemists, who are seeking to understand the function of these enzymes on a molecular level, inorganic chemists have been investigating the coordination chemistry of bi- and polynuclear complexes of manganese which contain O, N donor atoms and a variety of bridging O, N ligands. A large number of such complexes have been synthesized, their X-ray structures determined and their magnetic and spectroscopic properties studied in detail. In some instances the electronic and spectroscopic properties of these model compounds are amazingly similar to those of the biomolecules. This has led to a deeper understanding of the structure and sometimes of the function of the metalloproteins. Research on manganese metalloproteins with polynuclear active sites represents a fascinating example of interdisciplinary cooperation between physicists, biochemists and inorganic chemists.     

Cellulose--model films and the fundamental approach

This critical review describes the recent arrival of ultrathin films of cellulose. The methodology of preparation as well as the applications of the films for fundamental research is fully covered. The review places cellulose in a wider scientific context where cellulose research is no longer a field of interest for specialised scientists only. Cellulose and cellulosic materials should interest communities such as biochemists, physical chemists, surface chemists, organic chemists, polymer chemists and also physicists working close the disciplines mentioned. (149 references.).     

The habit of the pipe: a layperson’s view of the periodic table

Foundations of Chemistry - The Periodic Table of Elements is one of the greatest achievements of the human intellect but is far from a finished work. Generations of chemists and physicists...     

The atomic number revolution in chemistry: a Kuhnian analysis

This paper argues that the field of chemistry underwent a significant change of theory in the early twentieth century, when atomic number replaced atomic weight as the principle for ordering and identifying the chemical elements. It is a classic case of a Kuhnian revolution. In the process of addressing anomalies, chemists who were trained to see elements as defined by their atomic weight discovered that their theoretical assumptions were impediments to understanding the chemical world. The only way to normalize the anomalies was to introduce new concepts, and a new conceptual understanding of what it is to be an element. In the process of making these changes, a new scientific lexicon emerged, one that took atomic number to be the defining feature of a chemical element.     

Radioactively labelled metabolic substrates: A new tool for nuclear medical assessment of myocardial metabolism in vivo

Until the beginning of the last decade, nuclear medicine failed to contribute to diagnostic information in cardiology. This was not only due to technical problems, but also to difficulties of interdisciplinar approaches. This situation now has drastically changed, particularly during the past few years. The new impetus, which greatly benefits the patient, was made possible by improved instruments and electronic data processing, as well as by new radioactive indicators, new concepts of diagnostic evaluation of data, and a broad interdisciplinary cooperation among radiochemists, synthetic chemists, physicians, physicists, mathematicans and computer specialists.     

A century of progress in the sciences due to atomic weight and isotopic composition measurements

Even before the 20th century, a consistent set of internationally accepted atomic weights was an important objective of the scientific community because of the fundamental importance of these values to science, technology and trade. As the 20th century progressed, physicists, geoscientists, and metrologists collaborated with chemists to revolutionize the science of atomic weights. At the beginning of the century, atomic weights were determined from mass relationships between chemical reactants and products of known stoichiometry. They are now derived from the measured isotopic composition of elements and the atomic masses of the isotopes. Accuracy in measuring atomic weights has improved continually, leading to the revelation of small but significant variations in the isotope abundances of many elements in their normal terrestrial occurrences caused by radioactivity and a variety of physicochemical and biochemical fractionation mechanisms. This atomic-weight variability has now been recognized as providing new scientific insights into and knowledge of the history of materials. Atomic weights, except those of the monoisotopic elements, are thus no longer regarded as "constants of nature". At the beginning of the 20th century, two scales for atomic weights were in common use: that based on the atomic weight of hydrogen being 1 and that based on the atomic weight of oxygen being 16. Atomic weights are now scaled to (12)C, which has the value 12 exactly. Accurate atomic weights of silicon, silver, and argon, have enabled the values of the Avogadro, Faraday and Universal Gas constants, respectively, to be established, with consequent effects on other fundamental constants.     

头发元素分析的科学意义及医学应用价值

对近100年来头发元素分析发展历史作了简要回顾，并从头发元素水平代表身体元素总体水平、头发元素含量可以准确测定，以及头发元素分析可用于医学诊断等三个方面论述了头发元素分析的生物学基础及临床意义，重点介绍了中国科学工作者在实验研究和临床实践中的探索和发现。科学实践证明，头发元素分析不仅为揭开古代头发神话提供了解释基础，也为头发的现代应用提供了可靠工具和科学依据。