Conversations at Bedtime. 215. Bromine.
“What does “Br” mean, mummy?”
“Where’s that, darling?”
“I saw it in grandma’s letter.”
“Oh, yes. That’s the symbol for bromine, darling.”
“Grandma says in this letter that her chemistry teacher spilt bromine by accident out of a beaker and she was frightened, because it flowed over the teacher’s desk and onto the floor.”
“That’s because bromine is heavy and sinks down, darling.”
“It sounds like the bromine stretched out when it fell out of the beaker.”
“Well the bromine didn’t stretch out. It’s actually made up of lots of tiny things called atoms.”
“Oh, yes, I remember. Grandma said that atoms are really hard little lumps of stuff.”
“I wouldn’t call them hard lumps, darling. An atom is not really a lump. It’s made up of even smaller bits which are called electrons and protons and neutrons.”
“So does a bromine atom have those things inside?”
“Certainly. Quite a few really. Although I don’t remember how many of each. I can phone up the Royal Australian Chemical Institute and they might know.”
“How come atoms have all those things in them, mummy?”
“Well that is a very difficult question, darling. I don’t really know why. They just do.”
“But if an atom of bromine has lots of those things, doesn’t that make it a hard big lump, made up hard little lumps?”
“Well no, dear. The electrons are actually a long way from the other bits. The protons and neutrons are all stuck together in the middle and the electrons fly around outside.”
“That’s pretty weird.”
“That’s not even the weirdest part, darling. If you want to know the truth, electrons are not solid like a bit of rock. They are not even bits of stuff all the time, but are more like tiny, tiny clouds of light, surrounding the bunch of neutrons and protons in the middle.”
“Oh. Oh. So when we write “Br” does this mean that it’s an atom of bromine made up of clouds of light and a solid lump of stuff inside?”
“Let’s just say that the electrons can be bits of stuff and clouds of light at the same time, darling.”
“But how come we write “Br” and it means all that complicated stuff, mummy?”
“Well it’s shorthand, really. We can’t write down the full story of a bromine atom – or any other atom for that matter - every time we write chemistry language. It would take too long and take too much space.”
“But how can people who don’t understand chemistry know all this?” “Unfortunately this is the nature of writing chemistry, darling. It’s a foreign language for most people. We take shortcuts. Most of chemistry is written as metaphor.”
“What’s metaphor, mummy?”
“Well, in the case of chemistry, it’s a symbol that describes something as if it were something else.”
“Oh… I see… Yes… I think I will read the rest of grandma’s letter and then I can go to sleep.”
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Dr Michael P. Henry graduated from ANU with BSc. Honours and MSc. Graduated with PhD (University of Essex) in 1970. Lecturer in Chemistry, QIT, 1969 to 1981. Senior Scientist, J.T. Baker Inc, New Jersey, USA, 1981 to 1992.
Retired 2005.
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