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Despite the increasing interest in Italian medicine, comparatively little attention has been paid to the establishment of iatrochemistry. Though this process spread throughout the Peninsula, Naples witnessed an impressive growth of chemical research and the outbreak of a conflict between the medical establishment and the chemical physicians. The purpose of this article is to explore the emergence of chemical medicine in Naples in the period that precedes the founding (1663) of the Accademia degli Investiganti . In the first part of the seventeenth century, chemistry achieved recognition in settings like academies, pharmacies, hospitals, and monasteries. Chemical studies and the making of new remedies were spurred by the scientific exchange that Neapolitan savants established with scholars from different areas. The so-called medical pluralism and the recurrent outbreaks of epidemics stimulated the introduction of new chemical therapies, which coexisted with old ones . The establishment of chemical medicine was triggered by Marco Aurelio Severino (1580-1656), who, besides promoting chemical remedies, resorted to chemical theories, including Paracelsian ones, to account for physiological processes. Severino was the mentor of the chemical physicians who gave rise to the Accademia degli Investiganti . One of Severino's disciples was Giuseppe Donzelli (1596-1670), who fostered chemical remedies in Naples.

Chemical reaction networks (CRNs) are susceptible to mathematical modelling. The dynamic behavior of CRNs can be investigated by solving the polynomial equations derived from its structure. However, simple CRN give rise to non-linear polynomials that are difficult to resolve. Here we propose a procedure to locate the steady states of CRNs from a formula derived through algebraic geometry methods. We have applied this procedure to define the steady states of a classic CRN that exhibits instability, and to a model of programmed cell death.

This article is concerned with the public courses and lecture demonstrations given by Louis Jacques Thenard at the College de France during the first decades of the nineteenth century. The expectations and needs of Thenard's auditors will be studied in order to understand the role played by chemistry courses at the College in the context of the growing and changing Parisian teaching market during the first third of the nineteenth century. The preparation and performance of lecture demonstrations was the main driving force of several major changes in the premises and the personnel associated with the chair of chemistry. Our analysis of the parallel process of expansion and functional differentiation of spaces and personnel will show the multiple interactions taking place between the research and teaching activities developed by Thenard and his team of assistants and students.

An appreciation of Stanley L. Miller, the pioneer prebiotic chemist, who died last year.

The recovery of dissolved platinum group elements (PGE: Pd(II), Pt(IV) and Rh(III)) added to Milli-Q water, artificial freshwater and seawater and filtered natural waters has been studied, as a function of pH and PGE concentration, in containers of varying synthetic composition. The least adsorptive and/or precipitative loss was obtained for borosilicate glass under most of the conditions employed, whereas the greatest loss was obtained for low-density polyethylene. Of the polymeric materials tested, the adsorptive and/or precipitative loss of PGE was lowest for fluorinated ethylene propylene (Teflon). The loss of Pd(II) in freshwater was significant due to its affinity for surface adsorption and its relatively low solubility. The presence of natural dissolved organic matter increases the recovery of Pd(II) but enhances the loss of Pt(IV). The loss of Rh(III) in seawater was significant and was mainly due to precipitation, whereas Pd(II) recovery was enhanced, compared to freshwater, because of its complexation with chloride. The results have important implications regarding protocols employed for sample preservation and controlled laboratory experiments used in the study of the speciation and biogeochemical behaviour of PGE.

We propose a new concerted mechanism for the uncatalyzed hydrosilylation of terminal alkenes and alkynes, alternative to the conventional radical-based mechanism. Density functional calculations have been carried out on these and on previously proposed alternative mechanisms for the hydrosilylation of ethylene and acetylene by suitable finite size clusters as models of the thermal functionalization of -SiH3, =SiH2, and [triple bound] SiH groups in flat Si(100) and Si(111) and porous silicon surfaces by alkenes and alkynes. For each step involved in the considered hydrosilylation pathways, we optimized the geometries of reactants and products and located the corresponding transition states. The calculated activation energies for the concerted pathways of ethylene and acetylene are, respectively, 57.6 and 60.9 kcal mol(-1) on -SiH3 and in the ranges 62-63 and 58-61 kcal mol-1 on =SiH2 and 64-66 and 56-61 kcal mol(-1) on SiH. These values are much lower than the activation energies calculated for the corresponding homolytic dissociation of the Si-H bond, which is the preliminary step in the radical path, 85.6, 82-83, and 79-81 kcal mol(-1), respectively, for -SiH3, =SiH2, and [triple bound] SiH groups. Our results thus suggest that the thermal hydrosilylation of alkenes and alkynes on silicon surfaces, for which a radical-based mechanism is currently accepted, may occur through a concerted mechanism.

We report a theoretical study based on density functional theory (DFT) and time-dependent DFT (TDDFT) calculations on the nature and role of the absorption bands involved in the nonlinear optical response of the complexes [Ru(CF3CO2)3T] (T = T1, T2; T1 = 4'-(C6H4-p-NBu2)-2,2':6',2''-terpyridine, T2 = 4'-(C6H4-p-NMe2)-2,2':6',2''-terpyridine). Geometry optimizations, performed without any symmetry constraints, confirm a twisting of the -C6H4-p-NBu2 moiety with respect to the plane of the chelated terpyridine. Despite this lack of strong pi interaction, TDDFT excited states calculations of the electronic spectrum in solution provide evidence of a relevant role of the NBu2 donor group in the low-energy LMCT band at 911 nm. Calculations also show that the two bands at higher energy (508 and 455 nm) are not attributable only to LMCT and ILCT transitions but to a mixing of ILCT/MLCT and ILCT/pi-pi* transitions, respectively. The 911 nm LMCT band, appearing at lower wavelength of the second harmonic (670 nm) of the EFISH experiment, controls the negative value of the second-order NLO response. This is confirmed by our calculations of the static component beta0(zzz) of the quadratic hyperpolarizability tensor, showing a large positive value. In addition we have found that the increase of the dipole moment upon excitation occurs, in all the characterized transitions, along the dipole moment axis, thus explaining why the EFISH and solvatochromic experimental values of the quadratic hyperpolarizability agree as sign and value.

The purpose of this paper is to reconsider the issue of the creativity of textbook writing by exploring the links between nineteenth-century French textbooks and the quest for a classification of elements. The first section presents the elegant combination of didactic and chemical constraints invented by eighteenth-century chemists: the order of learning - from the known to the unknown - and the order of things - from the simple to the complex - were one and the same. In section two we argue that the alleged coincidence did not help the authors of elementary textbooks required for the new schools set up by the French revolution. Hence the variety of classifications adopted in the early nineteenth century. A debate between natural and artificial classifications raised a tension in the 1830s without really dividing the chemical community. Rather it ended up with the adoption of a hybrid classification, combining the rival natural and artificial systems.

Computer readable databases have become an integral part of chemical research right from planning data acquisition to interpretation of the information generated. The databases available today are numerical, spectral and bibliographic. Data representation by different schemes--relational, hierarchical and objects--is demonstrated. Quality index (QI) throws light on the quality of data. The objective, prospects and impact of database activity on expert systems are discussed. The number and size of corporate databases available on international networks crossed manageable number leading to databases about their contents. Subsets of corporate or small databases have been developed by groups of chemists. The features and role of knowledge-based or intelligent databases are described.

Cryogenic electron microscopy (cryo-EM) is a powerful technique capable of characterizing large protein complexes that are otherwise impossible to characterize using traditional crystallography methods. Cryo-EM has played a pivotal role in our understanding of the structure--function relationship of the spike proteins on the COVID-19 viral capsule, allowing for the rapid development of therapeutics and vaccines in our quest to end the COVID-19 pandemic. The relevance of cryo-EM to this global event advocates for its incorporation into undergraduate chemistry curricula. In fact, highlighting the importance and applicability of a technique to students allows for a better retention of knowledge. Therefore, in this laboratory exercise, we introduce the concepts and application of cryo-EM as a structural characterization tool in an upper-year undergraduate class. Furthermore, with the aid of three-dimensional (3D) printing, the concepts of tomography are introduced, allowing students to understand the construction of a 3D model from a collection of 2D images through cryo-EM. According to student responses, this lab module was well-received, and the 3D-printed model indeed added to their learning experience. While cryo-EM is a specialized technique that may not be available to some educational institutions, those with access should consider its incorporation into their curriculum, thereby exposing students to a breadth of structural characterization techniques that broaden their learning experience.

During the SARS-2-COVID pandemic our institution sought to continue the teaching and learning of experimental laboratories by designing, assembling, and delivering a microscale chemistry kit to the students' homes. Thanks to this approach students were able to perform [approximately]25 experiments during each one of the Fall 2020 and Spring 2021 semesters in an elective Electrochemistry and Corrosion course offered to Chemical Engineering undergraduates. In addition to performing traditional experiments, students were encouraged to design some of their own and have the entire group reproduce them. One of such student-designed experiments involved the capture of CO[subscript 2] and its reduction with a readily available active metal (i.e., Al foil) in aqueous media to generate potentially useful products. The highly negative standard potential of Al is exploited for the reduction of lab-generated CO[subscript 2], and the products are chemically tested. Al as a foil has been reported to be electrochemically inactive for carbon dioxide reduction. However, encouraged by an earlier report of the reduction of CO[subscript 2] to CO, the Al surface is activated in the present experiment by removal of its natural oxide layer with a solution of CuCl[subscript 2] produced in an electrochemical cell. This procedure enables Al to react with CO[subscript 2] and yield useful chemistry. This experiment turned to be a discovery trip. The detailed procedure is discussed here, as well as the teaching methodology, grading scheme, and student outcomes.

Alternative teaching methodologies are required for grade-9 students diagnosed with difficulties learning chemistry. This study examines the progress made in learning atomic structure by 11 Spanish Students Diagnosed with Learning Difficulties (SDLD, experimental group), including those with poor academic performance, specific learning difficulties in reading, writing, and mathematics, attention deficit hyperactivity disorder, and borderline intellectual disability according to the Spanish curriculum. The study was conducted as part of the Program for Improving Learning and Performance (PMAR) and utilized the game "Atomizados", specifically designed for this purpose. A written test on atomic structure was used to evaluate learning with three learning levels established (naïve, transitional, and informed). The findings indicate that 63.63% of the SDLD (experimental) achieved an informed learning level (understanding the internal structure of the atom) as a result of utilizing a generative learning strategy. The Mann-Whitney U test demonstrated that this learning was statistically significantly greater than that achieved by other students diagnosed with learning difficulties who did not use the game (SDLD control group). No significant differences were found between the SDLD experimental group and two other groups of grade-9 students with no learning difficulties (NSDLD control groups). However, differences were detected between SDLD (control) and NSDLD (control) in favor of the latter groups. The average for these control groups was a transitional level (identifying some elements of the atomic structure) in the best cases. SDLD (experimental) exhibited a very positive perception of the game's influence on learning chemistry, highlighting its attractiveness, interest, and potential for generating classroom participation.

Socio-scientific issues demonstrate the relationship between science, technology, and society by considering currently unresolved questions. The problem of plastics and their pollution is just one example with important implications for the planet. The aim of this paper is to revisit socio-scientific issues and see them as a way of developing citizens' critical thinking skills through chemistry education. In light of the problems posed by plastics, we present evidence tested with Spanish grade-8 students of how critical thinking skills can be developed through chemistry education in terms of the vision of chemistry, understanding acquisition, a holistic approach to problems, critical analysis of information, argumentation, decision making, personal autonomy, and communication. This study also presents some examples of how progress in the development of critical thinking by students has been evaluated.

Educational games have attracted attention as valuable didactic instruments since they combine a proven efficiency in learning improvement with a fun and enjoyable atmosphere. Despite the increasing number of educational game contributions treating a wide variety of topics, to the best of our knowledge, none revise units or physical quantities. "Unit Kemps" is a 4- to 12-player funny, engaging, easy-to-play, and trilingual (English, French, and Spanish) game. Based on the French card game "Kemps", the main goal of the game is to match 4 cards of a kind, in this case a physical or chemical quantity, its symbol, its unit, and the instrument used to measure it. More importantly, the game targets learning physical quantities and to distinguish among the physical property, the unit, and their respective symbols in an amusing and relaxing atmosphere. The game was tested by 47 first- and second-year students from the Facultad de Qui´mica at Universidad Nacional Autónoma de México (UNAM), with encouraging results in different aspects including content, playability, and engagement. Moreover, a pre- and postevaluation revealed an encouraging enhancement in memorization concerning the identification of physical and chemical quantities after playing the game. In summary, playing "Unit Kemps" might be a useful tool for students and educators to reinforce basic scientific curricula concepts and also to interact among them in a playful environment.

We describe a remote pedagogical approach based on chemical thinking to study metal-carbonyl complexes by analyzing simulated IR spectra. The proposed approach, implemented due to the COVID-19 pandemic, can be employed in classrooms that have very limited laboratory equipment for evaluating toxic metal-carbonyl compounds, as well as for synthesizing compounds that have not been reported. The method, consisting of a class lecture accompanied by a remote computational activity, aims to provide students with the ability to assemble concepts from different fields, such as organometallic chemistry and analytical chemistry, while taking advantage of computational methods to answer higher level questions. We evaluated whether analyzing the nature of M-CO bonding was appropriate for achieving these educational goals. Octahedral compounds of the M(CO)[subscript 6] and M(CO)[subscript 4]L[subscript 2] type, bearing a variety of metal centers (M = Cr, Mo, W, V, Mn and Fe) and ligands (L = phosphines and phosphites), as well as bimetallic Fe[subscript 2](CO)[subscript 9], were compared, showing how these modifications affect M-CO bonding. After the didactic session, attended by second-year and upper-division students of Facultad de Química at UNAM, an evaluation and survey showed that students improved their understanding of the subject when they obtained and visualized IR spectra, also exhibiting greater confidence and enthusiasm for addressing challenging topics. The combination of computational results, spectroscopic analysis, and organometallic theory represents an efficient and clear procedure for implementing chemical thinking, regardless of the difficulties posed by the COVID-19 pandemic.

A language is a system of communication, consisting of a set of sounds or written symbols that enable people to communicate. In chemistry, a particular language is required in order to represent the phenomenological world by means of symbols. Choosing the right words and knowing the precise definitions for chemical concepts is needed for avoiding misconceptions. Despite the creation of International Union of Pure and Applied Chemistry (IUPAC), fundamental notions are still undergoing constant debate, in particular concerning the conceptual distinction between element, atom, molecule, compound, chemical species and substance. In this article, we propose to better distinguish categories of chemical objects and their element, and to define a molecule as a stable and electrically neutral chemical entity that exists with a finite number of chemical bonds (0 to "n," with "n" finite number). This new definition implies that "noble gases," i.e., reduced to one isolated atom, are made of molecules, that all bonded atoms are atoms, and enables distinguishing both of these from "compounds." We insist that chemical education makes a clear difference between objects and categories, emphasizing the importance of understanding that elements and compounds represent categories of nuclei, whereas chemical entities and substances are a sample of matter. We also point out a number of nuances in chemical language, primarily in order to avoid misconceptions regarding the macroscopic physical properties relating to chemical substances and chemical objects.

Green chemistry is finding its place as one of the most essential study topics in the curriculum of future chemists and chemical engineers. Experiments that meet green chemistry principles contribute to make the laboratory a safer working place, generate less waste, and allow students to increase their knowledge in new environmentally friendly chemical methodologies. The work reported here focuses on the reductive opening of epoxides to afford the less substituted alcohols, which can be carried out at room temperature under catalytic conditions and using water as a hydrogen atom source. The results of this work, as well as a procedure which allows the initiation of students in the application of green chemistry techniques through a particular example, are reported. This laboratory practice can be used to teach organic and radical chemistry, green chemistry principles, and product analysis (thin layer chromatography, flash chromatography, [superscript 1]H NMR spectroscopy, and IR spectroscopy).

A virtual Game-Based Tournament of Chemistry was developed as an alternative to the traditional problem-solving classes to aid students in reviewing and understanding organic acidity and basicity concepts. The tournament was based on a multilingual virtual board game (English, Portuguese, French, and Italian) which aimed to facilitate students' interaction and collaborative learning in an enjoyable activity. The findings showed that students who participated in the tournament had better outcomes in the exams compared to those who partook in traditional problem-solving classes.

Educational games have demonstrated that they represent valuable pedagogical instruments, which can contribute to teaching and learning in a gratifying environment. In particular in chemistry courses, an important effort has been made to facilitate complex interrelated concepts in an easy, enjoyable, and sometimes competitive way. "Compounds and Molecules" is a two-player amusing, engaging, easy-to-play, multilevel and bilingual (Spanish and English) game. The main purpose of the game is to correctly guess the opponent player's card, but most importantly, to properly distinguish the conceptual differences between molecules and compounds and to learn general physicochemical information, including aggregation state of matter, polarity, color, miscibility/solubility in water, the nature of chemical bonding (covalent or ionic), and finally the geometry or crystalline structure of 50 common chemicals. The game was also tested on 20 teachers, who teach introductory Chemistry courses and 18 students from the Facultad de Química at Universidad Nacional Autónoma de México (UNAM), with positive results in terms of three main aspects: playability, content, and usefulness. Additionally, the students answered a brief quiz, before and after playing the game, revealing a slight improvement in knowledge related to correctly differentiating between chemical substances. In summary, playing this game may help students not only to reinforce basic chemistry concepts, but also to increase their general scientific knowledge.

The social dimension of chemistry is relevant and present in numerous socio-scientific issues, for example, the use of plastics. These issues can be covered at school by implementing strategies such as role-playing, which allow different perspectives to be understood, thereby helping to promote changes in attitude. This paper presents a pilot-study about the design and results obtained in the role-playing game "Should we ban single-use plastics?", which covers the problem of plastics in a secondary school chemistry class by way of argumentation and decision making. Role-playing allows students to represent the viewpoints of different important actors in this area both in favor of a ban on their use (fisherman, environmental scientist, teenager, biodegradable material manufacturer) and against (manufacturer of disposable surgical products, teenager, worker in a plastic cutlery factory, director of an oil company). This role-playing was implemented virtually for a class of grade-8 school students (secondary schoolers in Spain). The main findings include the promotion of learning about the chemical aspects of plastics and the change in attitude of some students regarding this issue after preparing and using arguments and counterarguments based on scientific evidence in a debate. Role-playing is well received by students and helps them to experience positive emotions. Students were found to be very critical of the issue addressed, and the COVID-19 pandemic appeared to affect their decisions.

YouTube is one of the most known and used social networks among students in the world, and undergraduate chemistry students are no exception. Undeniably, YouTube can offer several advantages for complementing university lessons in an asynchronous manner. There are many chemistry channels available on the internet; however, they are mainly too general or run by nonprofessionals, resulting in misconceptions or inaccuracies that lead to student confusion. In this contribution, we present CADMIO, a peer-to-peer reviewed YouTube channel with more than 60 videos in Spanish language, 2,550 subscribers, and 6,000 hours of accumulated views over the first year. These videos focus on introductory and advanced topics in inorganic chemistry. CADMIO is a powerful, versatile, and useful didactic tool, in which each video lesson presents basic concepts in a clear and concise way, thorough methodologies to enhance problem-solving skills, and an important variety of exercises to help students learning. The wonderful and outstanding response of CADMIO on the web and in the Faculty of Chemistry encourages us to improve the channel, and recently, it has even become a Social Service program in Mexico. Our unique concept for revised video content, secured by an editorial board consisting of professors at the Facultad de Qui´mica, UNAM, make CADMIO a truthful tool for teaching and learning chemistry.

In scientific and technical degrees, the opinion of the final employers on the given subjects is really important. For this reason, the Quality Committee (CQ) of the Faculty of Chemistry of the University of Barcelona prepared a survey for chemical, engineering and pharmaceutical companies asking about the academic training required by the companies. The survey consists of nine sections including items related to laboratory operations, chemical processes, calculation methods, management systems (quality, environment and safety) or general management information. In addition, at the end of each section, a question inquires the companies about the competences shown by students in the items of the section. The results were compared with those of a similar survey carried out in 2007. The scores obtained were between 2 and 3 for all the items (score: 1, not important; 2, less important; 3, important; 4, very important) and show that companies accept the training given to our students and the competences achieved by them. However, according to their opinion, it is possible to improve this training, especially in the subjects related to management (time, information, environment, quality, safety, etc.). Therefore, surveys are a good tool for the evaluation of the training achieved in our degrees and, consequently, for improving our teaching task, according to the Quality Management System implemented in the Faculty of Chemistry.

Due to the COVID-19 pandemic, social distancing restrictions are in place in most public settings, and the undergraduate laboratory is no exception. In order to accommodate social distancing requirements, many laboratory exercises are being redeployed in an online format, which deprives students of experiential learning opportunities in a real laboratory setting. To bridge this experiential learning gap for online laboratory exercises, an open-source remote titration unit was created. This remote titration unit is based on a simple Raspberry Pi architecture equipped with a webcam and a servo (a small motor allowing fine control of angular position), allowing students to control the titration unit over the Internet with visual feedback of approximately a 0.5 s delay. Understanding that titrations are taught across all levels of chemistry, from high school to the postsecondary level, they are considered fundamental laboratory methods in analytical chemistry. In fact, titrations are the first analytical chemistry technique introduced to students, and the method holds a significant place in the chemistry curriculum. In response to the recent emphasis on virtual lab platforms due to COVID-19, the chemistry laboratory will need to evolve accordingly. The remote-control titration unit described here is an exemplar, showing that elements of experiential learning can be retained for online laboratory activities, and allows for the possibility of distanced learning that includes a meaningful laboratory component.

An experimental procedure is presented that was developed by fifth-year chemical engineering and industrial chemistry undergraduates at the Federal University of Rio de Janeiro doing the discipline on Experimental Organic Technology. The aim of this study was to apply the solvatochromic effect of the dye Nile Blue chloride to the characterization of biodiesel/diesel blends with different biodiesel content, using an alternative image processing analysis method involving low-cost, simple, and rapid assays. The effect of the solvatochromic dye Nile Blue chloride was monitored using the software ImageJ, which is being used currently, yielding rapid and effective responses. As an outcome, the students proposed a procedure that had potential application to colorimetric determination of biodiesel content in diesel oil. This gave students the opportunity to put the knowledge acquired in the course into practice, by dealing with issues concerning the fuels industry, making the learning process more dynamic, engaging, and effective.

A remote experiment was developed and carried out to create a phenol/water phase diagram using a low-cost automated data collection system and an online video broadcast. Both the data and video from the experiment were transmitted in real-time. The remote lab experiment was evaluated using qualitative and quantitative questionnaires filled out by the students. The phenol/water phase diagram obtained is entirely consistent, with precision and accuracy compatible with what is expected to be achieved in conventional lab classes. The activity evaluation showed excellent acceptance by the students by doing this lab activity remotely.

The ability to visualize chemical processes can be an asset in a teaching laboratory. Despite the advances in laboratory technology, apparatuses used in the teaching of simple thermodynamics concepts, such as exothermic/endothermic reactions, historically remain unchanged and can benefit from a fresh perspective. The recent incorporation of thermal imaging cameras into the chemistry laboratory has enabled students to better grasp the concepts of thermodynamics. In fact, most visual learners will benefit from this approach, advocating its importance in undergraduate laboratory settings. However, most commercially available thermal imaging cameras are expensive, ranging from hundreds to thousands of dollars, which is a primary deterrent for their incorporation into the undergraduate chemistry curriculum. Therefore, in this technology report, we present a simple open-source Arduino thermal imaging system that can be assembled within $100 USD, bridging this affordability gap for instructors interested in using imaging technology in their classrooms. With the focus of STEM (science, technology, engineering, and mathematics) education in which coding literacy remains a top priority. This device and its construction can offer an excellent experiential-learning opportunity that incorporates the concepts of design thinking and coding, while exploring fundamental concepts in chemistry.

This article presents a qualitative study of the type and quality of questions formulated by prospective elementary teachers (PETs) when designing scientific inquiry activities, depending on the school science content selected. The data were acquired during teacher training instruction on these aspects with 67 participant PETs. The results showed that the PETs in general posit questions that are interesting, but not always conducive to starting some scientific inquiry in class. Within the set of high-order questions for inquiry (relating variables), it was found that those oriented to making predictions presented the most difficulties. The content the PETs selected to formulate questions covered a wide variety of topics or phenomena related to physics, chemistry, biology, and astronomy. The highest quality questions proposed in greater numbers were proposed in order to study Changes of State and Plants. Likewise, all the questions formulated about phenomena related to Flotation, Magnetism, and Gravity were of high order, while the poorest quality questions (not scientifically researchable) were related to the study of Machines. It was also found that the PETs frequently identified the variable with the object rather than with a property or magnitude. To conclude, some suggestions are made to improve teacher training with regard to inquiry-based science teaching and learning.

This study concerns a framework for designing Teaching-Learning Sequences that aims to integrate the implementation of scientific practices in the context of daily problems. Said framework consists of three stages (formulation of the design principles, instructional design and design of the learning activities). It is based on four design principles: (1) the context-scientific model relationship as the axis around which the teaching-learning sequence is based, (2) scientific practices as tools for treating the problem and constructing the scientific model, (3) use of driven questions, and (4) promotion of knowledge transfer. Similarly, the choice of context, the proposal of questions, the drafting of objectives, selection of knowledge, design of the sequence of activities and design of the evaluation are important during instructional design. This framework has been used to design a teaching-learning sequence based on learning the lactic fermentation model in the context of yoghurt preparation such that argumentation, inquiry and modelling play a key role in the educational treatment. Implementation of this teaching-learning sequence has shown an improvement in the lactic fermentation models proposed by Spanish students aged 14-16 years. These findings are considered to be initial evidence for the utility of the teaching-learning sequence and the framework.

Various international perspectives from selected regions where substantial work is being done on green and sustainable chemistry education emphasize a systems thinking framework. Common to most of the perspectives is the inclusion of more global paradigms involving economic, environmental, political, and social aspects as fundamental issues in the formerly merely technical and scientific discussions, as well as the development of laboratory experiences, training sessions, written materials, discussion meetings, and conferences. We include bird's eye views from Europe (the Green Chemistry Centre of Excellence at the University of York, United Kingdom; the University of Cordoba, Spain; and the University of Amsterdam, The Netherlands), Latin America (the Universidad Nacional de Rosario, Argentina, and the Universidad Iberoamericana, Mexico), Africa (the University of Venda, South Africa), and Australia (Monash University).

The learning of solving multi-step problems is a relevant aim in chemical education for engineering students. In these questions, after analyzing initial data, a complex reasoning and an elaborated mathematical procedure is needed to achieve the correct numerical answer. However, many students are able to effectively use algorithms even with a lack of meaningful understanding of involved chemical concepts. This paper reports the application of some collaborative actions in order to induce a complete acquisition of problem solving skills. The studied approaches, performed inside and outside the classroom, are classified in low-collaborative and high-collaborative activities, depending on the relative participation of instructor/students in their development. The critical description of the proposed methodology and the produced outcomes are exposed. The contribution of each major reasoning mode (model, rule or case based) employed in these activities is analyzed. Also, the perception of students is evaluated on the basis on the data provided by direct observation and a specific survey with Likert-scale and open-ended questions. The results indicate that the changes of teaching to a more conceptual orientation lead a deeper understanding, minimizing misconceptions or a rote learning.

Titration is a common introductory experiment performed across teaching laboratories from high school to university. Yet, its setup remains inaccessible for students with disabilities, denying them the opportunity for experiential learning. Therefore, rethinking such a setup is required to increase laboratory participation for these students. To remove these physical barriers, an automated titration unit based on existing undergraduate titration setups and universal design concepts, coupled with text-to-speech (TTS) capability, is presented. This unit can connect seamlessly via Bluetooth to any mobile platform and takes advantage of the advances in assistive features, such as TTS, on either a tablet or a smartphone. The cost of this unit is between $300 and $500, not including the cost of the smartphone or tablet. However, with the popularity of mobile devices in our society, these devices are becoming highly affordable, and almost every undergraduate is equipped with such a device. Also, with the emphasis on coding literacy, this autotitration setup serves as an excellent example and exercise on design thinking and automation in an undergraduate chemistry lab.

This work provides information about a free-of-charge, trilingual (Portuguese, Spanish, and English), game-based application. The game allows high-school and undergraduate students to review chemical nomenclature in an engaging and fun way on their own by answering random questions from a database with over 700 questions. Student testing revealed that the game design, content, playability, and usefulness was helpful as a complementary didactic tool to aid in traditional study. Assessment of student knowledge gains was performed. The results revealed that students who used the game as a complementary tool had higher performance in tests compared with students who studied nomenclature by only conventional learning methods.

"Escape ClassRoom "CSI 1.0"" is an educational escape room proposed as an interactive analytical chemistry exercise for the evaluation of undergraduate students at the end of the subject. This approach is a new form of live action learning activity in which the students have to solve an analytical problem, namely, "an alleged crime". From this initial hypothesis, they have to investigate the crime by playing the role of trainee forensic chemists. As in any escape room, "Escape ClassRoom "CSI 1.0"" is a logical game in which the main objective is to discover several clues, to find hidden objects, and to solve a mystery in order to escape a "locked" room in an established time. The students play the role of forensic scientists and solve the alleged crime by following the scientific method in order to escape. To do so, they have to apply the whole analytical process from beginning to end, i.e., from a correct sampling at the crime scene, through the analysis of sample and data treatment until the interpretation of the results to validate the initial hypothesis: a murder has been committed. If it has, then who did it? The students' knowledge in analytical chemistry and the teamwork are the only tools that they have to solve all of the riddles and uncover hidden messages to "win" while time is running out. This first experience showed the potential of an escape room to be used as an innovative educational tool easily applicable to other subjects.

Misconceptions of chemistry and chemical engineering university students concerning instrumental analysis have been established from coordinated tests, tutorial interviews and laboratory lessons. Misconceptions can be divided into: (1) formal, involving specific concepts and formulations within the general frame of chemistry; (2) operational/topical, dealing with specific capabilities, problems and operations in chemistry; (3) methodological, associated to peculiar methods of analytical chemistry and data treatment; and (4) social, regarding the relation of analytical data with the social frame. Such misconceptions define a non-structured view of analytical methods, procedures and protocols related with analytical instrumentation. Instruments are frequently viewed as an autonomous, error-free black box providing non-structured data with no need of calibration or control, whereas weak relationships are established between data and aims along the analytical process. (Contains 7 tables and 8 figures.) [Financial support for this paper was provided by the University of Valencia research project "Desarrollo de herramientas para el diagnostico y evaluacion de errores conceptuales y metodologicos en la ensenanza de la Quimica instrumental."]

This article presents a qualitative study, descriptive-interpretive in profile, of the effectiveness in learning about the nature of science (NOS) of an activity relating to the historical controversy between Pasteur and Liebig on fermentation. The activity was implemented during a course for pre-service secondary science teachers (PSSTs) specializing in physics and chemistry. The approach was explicit and reflective. Three research questions were posed: (1) What conceptions of NOS do the PSSTs show after a first reflective reading of the historical controversy?, (2) What role is played by the PSSTs' whole class critical discussion of their first reflections on the aspects of NOS dealt with in the controversy?, and (3) What changes are there in the PSSTs' conceptions of NOS after concluding the activity? The data for analysis was extracted from the PSSTs' group reports submitted at the end of the activity and the audio-recorded information from the whole class discussion. A rubric was prepared to assess this data by a process of inter-rater analysis. The results showed overall improvement in understanding the aspects of NOS involved, with there being a significant evolution in some cases (e.g., conception of scientific theory) and moderate in others (e.g., differences in scientific interpretations of the same phenomenon). This reveals that the activity has an educational utility for the education of PSSTs in NOS issues. The article concludes with an indication of some educational implications of the experience.

Box-and-whisker plots or simply boxplots are powerful graphical representations that give an overview of a data set. In this work five different examples illustrate the applications of boxplots in food chemistry. The examples involve relative sweetness of sugars and sugar alcohols with respect to sucrose, the potassium content of fruits and vegetables, amino acid content of egg white and yolk, chemical composition of freshwater and saltwater fish, and change in fatty acid composition of soybean oil through traditional cultivation or genetic engineering techniques. Readers are guided to identify through boxplots key features present in some foods associated with inorganic elements and molecules. It is certainly an interdisciplinary way of studying concepts of statistics, nutrition, and chemistry.

In this paper, the characteristics and results of a teaching unit based on the use of educational games to learn the idea of chemical elements and their periodic classification in secondary education are analyzed. The method is aimed at Spanish students aged 15-16 and consists of 24 1-h sessions. The results obtained on implementing the teaching unit are assessed with a focus on the development of students' understanding of the topics covered and their perceptions toward the role of games in the learning process. The data collection methods used included a learning assessment test (administered before the unit was started and one month after completion of the unit) and a questionnaire to assess the students' learning experience. As a complementary method to acquire data, the teacher keeps a diary. The main conclusion was that students progressed significantly in the areas of learning related to knowledge of the Periodic Table and its nature and history, but a lower level of progress was found in the application of knowledge and the use of evidence to draw conclusions. Furthermore, to some extent, the teaching unit helps to overcome learning difficulties associated with the study of this subject. In addition, most responses to the questionnaire indicated that students who followed the teaching unit with games achieved statistically better final results than those in the control group, who followed a traditionally taught program. A positive assessment was provided by students concerning the role of games in the proposed unit, and there were also positive perceptions regarding the influence of games on learning and their potential to encourage participation in the classroom. Finally, this research identifies a new type of educational resource, namely task involving play (TIP), that can be defined as intermediate between play and game scenarios. The TIPs may include artistic or technological creations by the student, and they allow the student to play an active role in the learning process. Such tasks help students to improve their learning through educational games, and they can be perceived as intermediate in terms of their simplicity, usefulness, attractiveness, and interest with respect to educational games.

The work reported here involved a comparative study regarding the understanding that high school students (16-18 years) have of the concept of chemical elements and their periodic classification. More specifically, the level of knowledge on this topic was compared before and after the completion of baccalaureate studies in a sample of Spanish students. In order to achieve this goal, a questionnaire was developed that included 14 items in an open format, through which various aspects of the students' understanding of the idea of chemical element and their periodic classification were assessed. In addition, the application of this knowledge to interpret and predict the behaviour and properties of elements and to carry out calculations on the atomic composition of the elements was evaluated. Aspects concerning the acquisition of scientific knowledge, the application of knowledge to different contexts and situations, and the use of scientific evidence to draw conclusions and knowledge about the nature and history of science were evaluated. The questionnaire was previously validated with a large group of students. The results of this study show that improvements occur primarily in addressing higher level cognitive questions (analysis, synthesis and evaluation) in comparison to the lower level tasks (capacity for retention, understanding or direct application of learning). In addition, students who start high school have a very limited understanding of the ideas behind the Periodic Table of the chemical elements and that their lack of understanding, to a large extent, remains upon completion of the baccalaureate. These results suggest that there are real difficulties in understanding this topic and show the limited influence of the studies completed in high school.

Spectrophotometry and colorimetry experiments are common in high school and college chemistry courses, and nanotechnology is increasingly common in every day products and new devices. Previous work has demonstrated that handheld camera devices can be used to quantify the concentration of a colored analyte in solution in place of traditional spectrophotometric or colorimetric equipment. This paper extends this approach to quantifying the concentration of gold nanoparticles in a colloidal gold "dietary supplement". With the addition of free Google applications, the investigation provides a feasible, sophisticated lab experience and introduction to nanotechnology.

The complex approximation is widely used in the framework of the Ligand Field Theory for explaining the optical properties of crystalline coordination compounds. Here, we show that there are essential features of these systems that cannot be understood with the usual approximation that only considers an isolated complex at the correct equilibrium geometry. We also show that a quantitative understanding of such optical transitions cannot, in general, be reached unless the internal electric field, E[subscript R](r), created by the whole crystal on active electrons confined in the complex, is also taken into consideration. Seeking to prove the key role played by this internal field, usually ignored in crystalline transition metal compounds, we focus on the origin of the color displayed by the Egyptian Blue pigment (CaCuSi[subscript 4]O[subscript 10]), the first ever synthesized by humans. This pigment, together with Han Blue (BaCuSi[subscript 4]O[subscript 10]), are chosen as model systems because the anisotropic E[subscript R](r) field produces huge shifts, up to ~0.9 eV, in their d-d transitions, which are unusual compared to the majority of compounds containing the same square-planar CuO4[superscript 6-] chromophore. The relevance of the internal field for explaining phenomena such as the distinct color of ruby and emerald or the optical spectrum of CuF[subscript 6][superscript 4-] complexes in layered perovskites is also emphasized.

This paper addresses the importance of evaluating evidence for enriching critical thinking in the chemistry classroom. The purpose of the study was to examine the usefulness of a historical chemical controversy in promoting students' assessment of evidence. The investigation was conducted in a high school in Melun, France. 63 participants (24 females and 39 males aged 16-17 years) evaluated evidence relating to the polemical question of who discovered oxygen, with Carl Wilhelm Scheele (1742-1786), Joseph Priestley (1733-1804), and Antoine Laurent de Lavoisier (1743-1794) being possible contenders. This evidence was provided by the play "Oxygen", written by Carl Djerassi and Nobel laureate Roald Hoffmann (2001a), and was classified as either experimentation in science or scientific communication. The findings indicate that this historical chemical controversy helped to raise the students' awareness of the essential role of evidence evaluation in the advancement of chemistry. Furthermore, they reveal that the participants evaluated "easier" evidence relating to experimentation in science rather than evidence relating to scientific communication. The main conclusion drawn from this study is that historical chemical controversies can enhance learners' assessment of evidence.

Podophyllotoxin, its derivatives and structural analogues are an extensive group of aryl-tetralin-lignans of interest in pharmacology due to their promising anticancer and antitumor activity. The synthesis methods that have been proposed to date seek to resolve synthetic, stereochemical, pharmacodynamic and environmental aspects. In this review we have updated and brought together different classifications of lignan and podophyllotoxin synthesis. Transformation methods focus on the strategies used to form or functionalize rings A, B, C and D, as well as the configuration of the system of four stereogenic centers that fuse rings C and D.