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Chemistry teachers face constraints when trying to integrate cognitive and affective objectives, and hence thoughtful lesson planning is required to achieve the goal. Chemistry teachers can educate students to be knowledgeable about chemical concepts, processes and the benefits of responsible practice by the chemical industry, while being aware, and prepared to act against hazards posed by the chemical industry or threats of chemical terrorism.

Previous studies have indicated that A-level students in the UK and Singapore have difficulty learning the topic of ionisation energy. A two-tier multiple-choice instrument developed in Singapore in an earlier study, the Ionisation Energy Diagnostic Instrument, was administered to A-level students in the UK, advanced placement high school students in the USA, and first-year university students in China, New Zealand, and Spain to determine whether the students from different countries and educational systems had similar conceptions and difficulties as the students in Singapore with the concepts assessed in the instrument. The results showed that, in general, the students in all six samples had similar alternative conceptions, which were grouped under the categories of octet rule framework, stable fully-filled and half-filled subshell conceptions, and conservation of force thinking. The students also resorted to relation-based thinking when answering items involving the trend of ionisation energies across Period 3. Implications for teaching and further research are discussed. [ABSTRACT FROM AUTHOR]

A study of the involvement of free oxygen radicals in trapping and digestion of insects by carnivorous plants was the main goal of the present investigation. We showed that the generation of oxygen free radicals by pitcher fluid of Nepenthes is the first step of the digestion process, as seen by EPR spin trapping assay and gel-electrophoresis. The EPR spectrum of N. gracilis fluid in the presence of DMPO spin trap showed the superposition of the hydroxyl radical spin adduct signal and of the ascorbyl radical signal. Catalase addition decreased the generation of hydroxyl radicals showing that hydroxyl radicals are generated from hydrogen peroxide, which can be derived from superoxide radicals. Gelelectrophoresis data showed that myosin, an abundant protein component of insects, can be rapidly broken down by free radicals and protease inhibitors do not inhibit this process. Addition of myoglobin to the pitcher plant fluid decreased the concentration of detectable radicals. Based on these observations, we conclude that oxygen free radicals produced by the pitcher plant aid in the digestion of the insect prey. [ABSTRACT FROM AUTHOR]

This article describes the development and application of a two-tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis. Qualitative analysis is a difficult topic for students to learn as it involves both process skills as well as the understanding of many chemistry concepts. Chemistry teachers in Singapore frequently complain that their students do not understand what they are doing in the qualitative analysis practical sessions; many students adopt a recipe approach, cannot carry out the experimental procedures properly, and do not understand the purpose of the experimental procedures. An example of students' lack of understanding of qualitative analysis was the examiners' comments that in procedures involving the addition of aqueous ammonia to the unknown samples, many students wasted time testing for ammonia gas which, not surprisingly, they were able to detect. However, at present, students can score high marks in qualitative analysis practical examinations without much understanding of qualitative analysis.