IB Docs (2) Team The 12 TOK concepts
Introduction
The main difference in TOK for first assessment in 2022 is that the framework of the TOK curriculum has shifted to become "concept-based." This means that the focus of the course is now on "big ideas." These big ideas are transdisciplinary in nature and help us to understand "why" we are learning the content.
The dozen TOK concepts
This page looks at the 12 concepts on which the TOK course is built. Some of the concepts link more directly to chemistry than others, but helping students to see how these concepts are relevant in chemistry will help to support the transfer of their understandings and make TOK a more relevant and integrated part of their DP learning. Many of examples given for the concepts are covered more thoroughly elsewhere on the site - particularly in many of the 'Something to think about' sections - and some links are included to these.
How certain can we be of anything in chemistry? Chemistry is an experimental science and whenever measurements are made they are associated with an inherent uncertainty. When carrying out individual investigations students are encouraged (required?) to work out the associated cumulative uncertainty and error in their processed data and yet when using data such as the values for Avogadro’s constant, the velocity of light and the gas constant they are all assumed to be certain values even though they too have been arrived at experimentally. Certainty is enhanced by replication. Only if an experimental result can be replicated can it be used reliably as evidence. Often data can produce certainty for how a large number of particles behave, such as the half-life of a radioactive isotope, but can give no certainty at all as to when an individual isotope will decay.
Supporting material: 5.1 Measuring energy changes
It may appear that chemists, as natural scientists, would be more objective in their research into substances than for example social scientists who study their own species. However, due to our culture and upbringing, all of us possess inbuilt bias and prejudices many of which we may be unaware of. It is worth examining how research is funded. For example, much research into the efficacy of certain drugs or medicines is funded by the companies they are mIB Docs (2) Teamfactured by and the sample size and make-up may have been manipulated unintentionally, or otherwise, to obtain a favourable outcome. Ways in which objectivity can be supported are peer review and replication, which involves repeating a study using the same methods but with independent experimenters.
Supporting material: Fish oil
Culture involves many aspects, such as a common heritage and history and a shared language. Chemistry has all of this and TOK is concerned with how culture affects our knowledge of the world around us. Our language is very specific and, in some cases prescribed (e.g. IUPAC), and even includes words such as spontaneous which have a very different meaning in chemistry from their everyday use. Chemistry grew out of alchemy and there is a rich history of people such as John Dalton, Antoine Lavoisier, Linus Pauling and Fritz Haber who have made major contributions to the development of chemistry. I’ve made up five fun quizzes on the Culture of Chemistry which will both test and increase your students’ knowledge and appreciation of our culture and how it affects our knowledge.
In chemistry there are two very different perspectives of the word ‘perspective’.
In the simple artistic sense perspective is the representation of three-dimensional objects on a two-dimensional surface so as to give the right impression of their height, width, depth, and position in relation to each other. This is important when it comes to modelling three-dimensional molecules on a screen or paper. Diagrams in two-dimensions can cause confusion when showing the movement of pairs of electrons (curly arrows) in reaction mechanisms where Walden inversion is involved and also make bond angles which are really 109.5o appear as 90o when representing alkanes.
‘Perspective’ in the 12 TOK concepts sense though probably refers to the way in which attitude or point of view comes into play. How often do we assume that everyone else sees chemistry in the way that we do? There was once an IB question on the Environmental option in Paper 3 asking how a householder could save water. The official mark scheme gave “put a brick in the toilet cistern” or “take a shower rather than a bath” as the answer. The person setting the question had not even considered those parts of the world where fresh water is scarce and contains homes that do not have showers, baths and toilets, let alone taps with running water.
Supporting material: 20.1(1) Nucleophilic substitution and Topics 10 & 20
It is often stated that the atomic theory was first proposed around 400 BCE by Democritus. There is some logic behind Democritus’s proposal as when you divide matter it will either be continually divisible or there will come a point when it can no longer be divided. However Democritus had no evidence to support his theory. Some 2200 years later Dalton provided the first evidence when he measured the weights of substances as they broke down or combined with other substance. Atoms are too small to be seen with the naked eye but even if they could, would it be conclusive evidence that they exist? As science has progressed more and more evidence has accumulated (e.g. the use of scanning tunnelling microscopy) to support the atomic theory of matter.
Evidence matters as it enable models to be made from which predictions can be extrapolated. For example, measurements of the precise wavelengths of the emissions in the visible hydrogen spectrum led to the Rydberg equation. From this equation it was deduced that other series of lines in the ultraviolet and infra-red regions of the spectrum also exist even though no-one had ever seen them before. These series of lines provide the evidence that electrons in an atom can only exist in certain fixed energy levels.
Supporting material: 2.1 The nuclear atom and 12.1 Electrons in atoms
The knowledge and ability to make use of and manipulate substances, whether natural or man-made, has always given mankind power. Chemists literally hold power of life or death. Over the past two hundred years the large increase in life-expectancy has come about mainly through advances in chemistry such as the provision of clean drinking water through disinfection and the use of drugs such as penicillin to combat infection. The birth control pill has given women much more control over their own bodies. Conversely the last two hundred years has also seen the use of chemical weapons in warfare, the illicit use of new poisons such as sarin and novichok and the unintentional rise in deaths and disability caused by pollutants. The power of chemistry has a major effect on how society itself functions and develops – the clothes we wear, the food we eat and the fuel we use are all largely determined by chemistry.
Supporting material: B.1 Introduction to biochemistry
Explanations are our attempt to understand why substances behave in the way that they do and how we communicate this understanding to others. Explanations in chemistry are often at different levels. Chemists frequently use models in explanations and the level of sophistication of the model may depend upon the knowledge, maturity and understanding of the student or teacher. Simple models of covalent bonding involving the octet rule work in many cases but this simplified approach breaks down when it comes to predicting the paramagnetic properties of oxygen. More sophisticated explanations, such as those involving molecular orbital theory, also require an understanding of mathematics (e.g. second order perturbation theory and the use of Hamiltonian operators) which is beyond school level.
Supporting material: 4.3 Covalent structures (2) A modern paradigm
How do chemists interpret their data? Students are generally encouraged to obtain quantitative data rather than qualitative data and to manipulate their data by taking logarithms or reciprocals etc. to try to obtain a straight line of best fit. This means they can then use the graph to extrapolate, interpolate or to take a gradient from which deductions can be made. This focus on quantitative data ignores some important aspects of chemistry. Many compounds have a unique smell and yet there is no specific measurement of smell so reliable predictions of unknown smells cannot be made from interpreting graphical data. Even when quantitative data is interpreted there is a danger of wrong interpretation. There may be a need to distinguish between causality and correlation, particularly if all the controlled variables have not been adequately controlled.
Supporting material: 11.2 Graphical techniques
As chemists we should strive to be true to ourselves, i.e. perform experiments and record results without any attempt to manipulate the data to obtain the results we hope for to support a particular hypothesis. However we may inadvertently bring bias into our experimentation and, as Popper had elucidated, no experiment can ever prove a theory so the aim of all experimentation should be to disprove, not prove. Ultimately there is no incontrovertible truth in chemistry. All we can strive for are approximations that refine and become ever closer to ‘the truth’. At points in time certain axioms are taken as true, e.g. when substances burn in air they give off phlogiston, but as chemistry evolves ‘the truth’ changes so that the current paradigm explains combustion as combination with oxygen. Sometimes we accept statements as true even when we know they are not as they enable us to make sensible deductions within our own framework of knowledge. For example, the use of Lewis structures and VSEPR theory for the bonding and shapes of simple molecules and ions relies on all the valence electrons being equal. We assume this even though we know that s and p electrons with the same principal quantum number have different shaped orbitals and their sub-levels have different energies.
Supporting material: Topics 4 & 14 and 4.3 Covalent structures (2)
Justification involves making links between theoretical frameworks and choices. For IB chemistry students this a key part of the IA scientific investigation or an extended essay in chemistry. They need to justify why they are investigating a particular topic and why they have framed their research question in the way that they have. They also need to justify their research methodology – why the particular method was chosen and why other possible ways of investigating the research were discarded. Research chemists working in industry will often be called upon to justify why their research is relevant to the particular company (i.e. whether it will be profitable) before they can proceed. In cases like this perhaps financial justification can hinder research into blue sky topics which involves knowledge for its own sake without any clear benefit being obvious beforehand. Those in academia may have less need to justify their choice of research topic and the irony is that sometimes through serendipity their research can lead on to successful industrial spin-offs including life-saving drugs such as penicillin and cis-platin.
Supporting material: D.2 Aspirin & penicillin and Discovery of cis-platin
Values are fundamental beliefs that guide or motivate attitudes or actions, so the concept of values is very much linked to culture and perspectives. Often chemists have faced a moral dilemma over which of their beliefs they value more. Fritz Haber believed in patriotism and therefore thought it was right to work on poison gases to help his country win the 1914-1918 world war, his wife Clara and other chemists thought it was wrong to work on methods of mass destruction. A similar choice is facing chemists now. There is an urgent need for specific metals such as cobalt, manganese, nickel and copper for the green technologies to reach net zero carbon emissions to reduce, or at least contain, global warming. The best source is the coal-sized nodules found on the seabed but deep-sea mining runs the risk of causing environmental chaos by destroying vast swathes of marine life. These choices need to be made by society as a whole, not just chemists. Society needs to be informed by the scientific knowledge in order for it to determine the priority of its values.
Supporting material: Should deep seabed mining be allowed?
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