4
$\begingroup$

My 7 year old nephew found a chemistry text book and started copying some pictures and diagrams. He drew this and asked me what do the asterisks mean ? He said he normally sees letters which means atoms. But he can't found an atom that called "asterisks" from the periodic table.

enter image description here

Improve this question
$\endgroup$
11
  • 2
    $\begingroup$ Asterisk some times indicates an excited molecule in spectroscopy. It is not an element. In this particular case, this asterisk appears to have a decorative purpose only. $\endgroup$
    – ACR
    Commented Nov 27, 2021 at 17:47
  • 12
    $\begingroup$ Your nephew is apparently showing a polymer, with -CH2-CH2- repeating units. $\endgroup$
    – ACR
    Commented Nov 27, 2021 at 17:48
  • 5
    $\begingroup$ We shall commit to enroll him in a couple of years $\endgroup$
    – Alchimista
    Commented Nov 27, 2021 at 19:37
  • 4
    $\begingroup$ It is not an asterisk. It means "repeating the central unit -CH2-CH2- a lot of times, without any changes". $\endgroup$
    – Maurice
    Commented Nov 27, 2021 at 20:53
  • 3
    $\begingroup$ @Alchimista, he seems more prepared now that many other questioners. "Give me the child and I'll give you the chemist," as Aristotle stated (or was it Democritus? Dalton??). $\endgroup$
    – DrMoishe Pippik
    Commented Nov 28, 2021 at 0:45

1 Answer 1

Reset to default
0
$\begingroup$

Context

Because the structure your nephew has copied is a polymer, it is a huge chain of repeating units. There are so many units in the chain that you actually can't draw all of them. An inidcation that this is a polymer is the n in the formula.

What does it mean

Technically, what it would look like would be a long line of repeating CH2 units in the polymer however the asterisk is used to represent all of those CH2 units without having to draw it.

Modernized standards

Search up polymer diagrams and when you see a polymer diagram, rather than using an asterisk you might often see the central bit that got drew in brackets showing it is the repeating unit with lines pointing out of it. This a polymer diagram used to show a structure that consistently repeats in the polymer

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.