heisenberg uncertainty principle chemistry

On the other hand, when we attempt to observe these systems, they appear to be localised particles, something like bullets in the classical realm. Leave them to evolve by themselves without human interference, and they act like delocalised waves in the shape of continuous clouds. According to quantum theory, the building blocks of matter – like electrons, nuclei and the molecules they form – can be portrayed either as waves or particles. Misconceptions feeding the idea of the empty atom can be dismantled by carefully interpreting quantum theory, which describes the physics of molecules, atoms and subatomic particles. To be fair, you will also find a reasonable share of articles debunking the idea. Google ‘atoms empty space’, and you will find tens of essays, blog posts and YouTube videos concluding that atoms are 99.9 per cent empty space. Of the 180 voters, 43 per cent answered that they mostly agreed, and 27 per cent fully agreed. While preparing this essay, I ran a poll on Twitter asking whether people agreed with Sagan’s quote above. Today, as a professional theoretical chemist, I know that Sagan’s statements failed to recognise some fundamental features of atoms and molecules. I still remember how deeply these words spoke to me when I heard them as a kid in the early 1980s. After wondering how small the nuclei are compared with the atom, Sagan concluded that ost of the mass of an atom is in its nucleus the electrons are by comparison just clouds of moving fluff.

It is unclear who created this myth, but it is sure that Carl Sagan, in his classic TV series Cosmos (1980), was crucial in popularising it. The empty atom picture is likely the most repeated mistake in popular science. Atomic nuclei in a molecule are not tiny dots, and there are no empty spaces within the atom. How often have you seen such a scene or read something equivalent to it in popular science? I am sure plenty, if you are fans of this genre like me. The narrator lectures that the nucleus of an atom is tens of thousands of times smaller than the atom itself, and poetically concludes that we are made from emptiness. An initially imperceptible tiny dot grows smoothly, revealing the atomic nucleus. The camera focuses on a single atom within the strand, dives into a frenetic cloud of rocketing particles, crosses it, and leaves us in oppressive darkness.

The camera zooms in on the person’s arm to reveal the cells, then a cell nucleus.

Heisenberg uncertainty principle chemistry