Introduction to modelling at macroscopic and sub-microscopic levels: pressure in syringes (see PALAVA experiment below) The PALAVA project -a method of assessing modelling capability
The survey work is well described in this article.
This could move on to looking at volume and temperature changes, perhaps by thinking about the expansion of a balloon on the top of a flask immersed in warm water. This is further explored in the topic on instruments.
History:
Both Boyle and Torricelli in the 17th century created models of air based on numerical data about air, e.g. the effect of pressure on air volume at a fixed temperature. Bernoulli developed these in 1738. Biographies from Wikipedia Robert Boyle, Evangelista Torricelli, Daniel Bernoulli. These biographies are tough reading. Constructing simpler ones could be a project development.
Philosophy:
Conceptual modelling that is qualitative, that is, does not need numerical data, is often the first kind that a learner meets. However, an advantage of quantitative modelling is that it enables a much more challenging testing of the modelling process. Quantitative modelling also provides opportunity for simulation-type modelling using, for example, interactive animations and spreadsheets.
This section focuses on the macroscopic features of chemistry. A major issue is linking Direct Access observations with the invisible sub-microscopic particle models that we use to explain the phenomena.
The SEP gives this description
'As will become apparent, “scientific explanation” is a topic that raises a number of interrelated issues. Some background orientation will be useful before turning to the details of competing models. A presupposition of most recent discussion has been that science sometimes provides explanations (rather than something that falls short of explanation—e.g., “mere description”) and that the task of a “theory” or “model” of scientific explanation is to characterize the structure of such explanations. It is thus assumed that there is (at some suitably abstract and general level of description) a single kind or form of explanation that is “scientific”. In fact, the notion of “scientific explanation” suggests at least two contrasts—first, a contrast between those “explanations” that are characteristic of “science” and those explanations that are not, and, second, a contrast between “explanation” and something else. However, with respect to the first contrast, the tendency in much of the recent philosophical literature has been to assume that there is a substantial continuity between the sorts of explanations found in science and at least some forms of explanation found in more ordinary non-scientific contexts, with the latter embodying in a more or less inchoate way features that are present in a more detailed, precise, rigorous etc. form in the former. It is further assumed that it is the task of a theory of explanation to capture what is common to both scientific and at least some more ordinary forms of explanation. These assumptions help to explain (what may otherwise strike the reader as curious) why, as this entry will illustrate, discussions of scientific explanation so often move back and forth between examples drawn from bona-fide science (e.g., explanations of the trajectories of the planets that appeal to Newtonian mechanics) and more homey examples involving the tipping over of inkwells.'
Clues about compounds: law of constant composition as an indicator of atoms
Clues about law of conservation of mass: efforts to represent atoms.Third level of representation i.e. symbolic.
History: Constructing simpler articles could be a project development. It is vital that the learners study the process of induction during this exercise and gain some expertise in it.
The philosophical process is one that is well known and involves generalising. Induction is the process by which ideas about atoms were proposed to explain constant composition of compounds.
The challenge in this topic is to explain how to move from the law of constant composition to the atomic view of matter. This is clearly very difficult - it took scientists a long time to reach the atomic conclusion.
Chemical change and its representation in equations. Chemical equations v mathematical equations
Given incompleteness of chemical reactions, can equations be balanced? A major problem in traditional quantitative analytical chemistry was to ensure firstly that the materials used were pure, and secondly, that the reaction used for calculations proceeded 100% as written. A separate page will explore the issues in balancing equations, for teachers in the first instance.
Traditionally, chemical change is based on macroscopic identifiers, but researchers suggest that it is only at the symbolic level that it can be understood, and then not so easily. This needs to be brought out in the discussions.
Chemical equations are different from mathematical equations. Exploring these differences is part of this exercise.
Signs in chemical equations; origin and use.
Thermal decomposition of copper(II) carbonate is the base for this section. It was the base for chemical education research at the University of Reading.
Philosophy: Semiotics for beginners - nature of signs
All of the web sites visited on 2 Dec 08, by Googling 'Chemical Notation', focused only on expressions of formulae, and not on the signs, such as arrows, and +. The Braille site is mainly concerned with arrows. there are many computer sites concerned with mark up of chemical formulae but not signs.
As stated above, mathematical and chemical equations are not parallel. Thus, the signs in chemical equations need to be understood, and the dichotomy brought out into the open.
Computer animations of chemical processes - a step in representation
Modelling Learners
The PALAVA project -a method of assessing modelling capability
The survey work is well described in this article.
This could move on to looking at volume and temperature changes, perhaps by thinking about the expansion of a balloon on the top of a flask immersed in warm water. This is further explored in the topic on instruments.
Both Boyle and Torricelli in the 17th century created models of air based on numerical data about air, e.g. the effect of pressure on air volume at a fixed temperature. Bernoulli developed these in 1738. Biographies from Wikipedia Robert Boyle, Evangelista Torricelli, Daniel Bernoulli. These biographies are tough reading. Constructing simpler ones could be a project development.
Philosophy:
Conceptual modelling that is qualitative, that is, does not need numerical data, is often the first kind that a learner meets. However, an advantage of quantitative modelling is that it enables a much more challenging testing of the modelling process. Quantitative modelling also provides opportunity for simulation-type modelling using, for example, interactive animations and spreadsheets.
The notion of scientific explanation (SEP) embodies ideas about modelling. See the last part of this table for further links.
SEP Models in Science
The SEP gives this description
'As will become apparent, “scientific explanation” is a topic that raises a number of interrelated issues. Some background orientation will be useful before turning to the details of competing models. A presupposition of most recent discussion has been that science sometimes provides explanations (rather than something that falls short of explanation—e.g., “mere description”) and that the task of a “theory” or “model” of scientific explanation is to characterize the structure of such explanations. It is thus assumed that there is (at some suitably abstract and general level of description) a single kind or form of explanation that is “scientific”. In fact, the notion of “scientific explanation” suggests at least two contrasts—first, a contrast between those “explanations” that are characteristic of “science” and those explanations that are not, and, second, a contrast between “explanation” and something else. However, with respect to the first contrast, the tendency in much of the recent philosophical literature has been to assume that there is a substantial continuity between the sorts of explanations found in science and at least some forms of explanation found in more ordinary non-scientific contexts, with the latter embodying in a more or less inchoate way features that are present in a more detailed, precise, rigorous etc. form in the former. It is further assumed that it is the task of a theory of explanation to capture what is common to both scientific and at least some more ordinary forms of explanation. These assumptions help to explain (what may otherwise strike the reader as curious) why, as this entry will illustrate, discussions of scientific explanation so often move back and forth between examples drawn from bona-fide science (e.g., explanations of the trajectories of the planets that appeal to Newtonian mechanics) and more homey examples involving the tipping over of inkwells.'
Clues about law of conservation of mass: efforts to represent atoms.Third level of representation i.e. symbolic.
Learners carry out the traditional magnesium oxide combustion experiment.
A typical worksheet.
A set of official UK instructions and other guidance.
Wikipedia: John Dalton's symbols)
Berzelius paper (tough) on Law of Constant Composition
Proust's paper on analysis of copper carbonate. He works in old Imperial units of weighing matter, i.e. pounds and grains.
English translation of original report of Chemical Congress at Karlsruhe, Germany, 1860
Law of constant composition (definite proportions) from Wikipedia
See pictures of balances from Science and Society picture library
Jean Stas' translated 1860 paper on Atomic Weights
Atomic Thery of Matter: John Dalton, moderately readable at the Intute web site
Modern atomic theory of matter: a second page at the Intute web site, rather tougher reading.
Philosophy:
This article on Law of Constant Composition makes clear why formulating this law was tough at the time.
The philosophical process is one that is well known and involves generalising. Induction is the process by which ideas about atoms were proposed to explain constant composition of compounds.
A good experiment to perform here is the reaction between iron filings and copper(II) sulphate solution, to check whether iron(II) or iron(III) sulphate is formed.
A US version with sample data is here.
A Greek version as a worksheet (in English)
A second, well-written version from the US is here.
Issues about balancing equations.
Wikipedia: Jon Berzelius' fundamental work including his symbolic forms that represent elements and atoms.
Chemical Heritage Foundation on Lavoisier
First chemical equation (1615) by Beguin
Biography of Cullen (1710-1790) (used diagrams as chemical equations)
Biography of Lemery (1645-1715)
Philosophy:
Induction explanation from Intute web site
Given incompleteness of chemical reactions, can equations be balanced? A major problem in traditional quantitative analytical chemistry was to ensure firstly that the materials used were pure, and secondly, that the reaction used for calculations proceeded 100% as written. A separate page will explore the issues in balancing equations, for teachers in the first instance.
Chemical equations are different from mathematical equations. Exploring these differences is part of this exercise.
Thermal decomposition of copper(II) carbonate is the base for this section. It was the base for chemical education research at the University of Reading.
Various files will be uploaded and tagged here.
History of + sign in chemical equations
History of chemical arrows
Braille chemical signs and symbols
Philosophy:
Semiotics for beginners - nature of signs
All of the web sites visited on 2 Dec 08, by Googling 'Chemical Notation', focused only on expressions of formulae, and not on the signs, such as arrows, and +. The Braille site is mainly concerned with arrows. there are many computer sites concerned with mark up of chemical formulae but not signs.
ChemSense The ChemSense team are one of the first to explore representing chemical equations using bespoke software.
Philosophy:
Nature of representation
The Stanford Encyclopedia of Philosophy (SEP) articles have a strong scholarly base but are fairly tough going for the uninitiated. A few of the vast number of relevant pages are given below.
SEP on nature of diagrams (very tough going)
SEP on Mental Representation
SEP Models in Science
SEP Representation and Mental Imagery
SEP Einstein on Representation
Lots of chemical animations but no discussion
US web site for high schools
ChemiVis web site for high school
Eric Martz top 5 visualisation software
Wiki site for chemical visualisation tools - it is regularly updated
History of chinese animation
Wiki history of animation
Chronology of animation
Periodic Table animations