Non-binary electrons

On the final day of term, a member of my form tested me with a series of science jokes, the first of which was; “Why does a beef burger have less energy than a steak?” Pause here if you want to come up with your own solution. I must admit that I didn’t guess the punch line and the student added “whatever that means” when she revealed the answer. Aside of a little mirth, the joke also provides a good example of simplification within the school science curriculum that deserves a brief explanation.

The answer to the riddle is, a burger has beef in its ground state.

School science lessons, in both physics and chemistry, generally teach that atoms have electrons that are held in circular shells and that these electrons can be removed, or added to, to create ions that have full electron shells. But in fact electrons can be “partially removed” (for want of a better expression) by being given enough energy to move them further from the nucleus without becoming completely freed.

Such electrons are said to be in an excited state. And those electrons that have not been excited to any extent are said to be in the ground state. So atoms that have ground state electrons store less energy than atoms with excited electrons – and, of course, the word “ground” can also refer to a food-stuff that can been broken into small pieces, as required for preparing beef burgers.

The existence of ground state and excited electrons doesn’t really feature in GCSE sciences but it definitely does crop up later so, even at this stage, it’s worth knowing that electrons have non-binary characteristics that extend beyond simply being attached to, or separated from, their host atoms.