#Element definition chem how to#

For one thing, the four elements attributed to Empedocles and enshrined in Aristotle’s philosophy were by no means the only scheme for the basic building blocks of matter in Greek thought. The popular story has it that the ancient Greeks thought there were just four elements – earth, air, fire and water – but that from around the eighteenth century we began to appreciate that there are rather more than four, and that none corresponds to these ancient elements. Like the idea of atoms, elements suffer rather than benefit from an illusion of continuity in a long tradition of thought. So it seems reasonable to expect chemistry to provide an unambiguous definition.’ Can it, though? Earth, wind and fire? ‘For example, it identifies what stays unchanged in a system undergoing a chemical transformation, and it distinguishes between chemical and nuclear changes. ‘The notion of an element is central to chemistry and serves a number of purposes,’ Ghibaudi says.

#Element definition chem how to#

‘I don’t know how to make it clear to the public that only some compounds of a given element are toxic, and even that only above some particular concentration, while too little of that same element may even cause health problems,’ he says. Schwarz points to how, because some elements become associated with toxic substances – chlorine gas, say, or sulfur in the sulfur dioxide released from burning coal and oil – the element itself may become regarded as inherently toxic, and vulnerable to chemically illiterate bans. There could be problems for the public understanding of chemistry too. ‘When two experts in chemistry are discussing elements, they are able to distinguish the meaning from the context, but this is not so in the classroom,’ she says. Likewise if I say ‘Sulfur is the second element in group 16 of the periodic table.’ But these are two rather different things.Īccording to theoretical chemist Eugen Schwarz of the University of Siegen in Germany, the typical attitude is to say ‘I know how I speak about elements isn’t really correct, but everyone does it, and students will figure it out in the end.’ But ‘my personal feeling as a chemist is that one should not adopt this habit’, he adds.Įlena Ghibaudi of the University of Turin in Italy worries that this failure to define an element precisely raises problems of understanding, communication and trust in teaching. If I say ‘Sulfur is an element that forms a yellow solid with a pungent smell,’ I don’t expect objections. Some might say: who cares? We know what we mean in practice. We agree (right?) that hydrogen is an element – but what do we mean by that? Is molecular hydrogen gas an element? Or the isolated hydrogen atom? Or are we referring not to some actual substance but to a ‘transcendental’ notion of hydrogen of which actual atoms and molecules are just material representatives?

The meaning of an ‘element’ is a favourite topic for argument among off-duty chemists. It seems reasonable to expect chemistry to provide an unambiguous definition ‘There’s a need for philosophical reflection on aspects of chemistry that we tend to teach in a rather mechanical way,’ says Eric Scerri of the University of California Los Angeles in the US, editor of the philosophy of science journal Foundations of Chemistry. It’s not just the definition of an element concepts such as molecules, bonds, and even the character of the periodic table itself, remain fuzzy: deceptively familiar from regular use by practitioners, but lacking any meaning that everyone agrees on. ‘Chemistry does not understand itself as a discipline,’ says philosopher Farzad Mahootian of New York University in the US. And some of the participants of the meeting implied that this might be for the best.įor others, it’s an indication that chemistry has some serious philosophical thinking to do.

Some of chemistry’s finest minds, including Antoine Lavoisier, Mendeleev himself, and pioneer of nuclear chemistry Frederick Soddy, have grappled with it, yet still a concise and comprehensive definition remains elusive. The question was debated with much vigour and occasional passion during a meeting of the International Society for the Philosophy of Chemistry in Bristol in July 2018 – but still without producing any consensus. And yet no one can say quite what an element is. It’s one of the first ideas that the chemistry student encounters, often in the iconic tabulation of these basic ingredients of nature that Dmitri Mendeleev first described 150 years ago and which is being celebrated this year.

As chemical concepts go, you don’t get much more fundamental than the element.