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Atoms of Fire: What makes salt and sugar so different?

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Man holds up beaker in laboratory
Atoms of Fire: What makes salt and sugar so different?

SUBJECTS:  Science

YEARS:  7–8, 9–10


Have you ever accidentally sprinkled sugar on your dinner or spooned salt into your coffee?

Those white crystals might look the same but they taste very different because they are made of different kinds of atoms bonded in different ways.

Discover how chemists identify what kinds of atoms a compound is made of, then find out why an organic compound like sugar is much more difficult to analyse than an inorganic one like salt.


Things to think about

  1. 1.An element is a pure substance made of only one kind of atom. Can you name some elements? A compound is a substance in which different kinds of atoms are bonded together. How do you know that salt (NaCl) and sugar (C12H22O11) are both compounds?
  2. 2.Watch out for the notation that Jöns Berzelius invented. What does the 2 mean in H20? Of salt and sugar which is the organic compound? Spot the elements found always, often and sometimes in organic compounds. Listen for the word 'isomer' and for what that word means.
  3. 3.Explain how organic compounds differ from inorganic ones, using sugar and salt as your examples. Liquid ethyl alcohol and the gas dimethyl ether are isomers with the same formula (C2H6O). How is it that compounds with the same formula could have such different properties?
  4. 4.

    Carbon forms 4 bonds; oxygen forms 2 bonds and hydrogen 1. Use these rules to work out two different ways in which the atoms in the formula C2H6O could be bonded together. Look up dimethyl ether and ethyl alcohol and decide which compound has which arrangement.



Date of broadcast: 13 Aug 2001


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