JOHANN VAN HELMONT (1579-1644)

1621 – Brussels, Belgium

Portrait of  JOHANN VAN HELMONT

JOHANN VAN HELMONT

‘There are gases other than air’

Van Helmont coined the term ‘gas’.

He hypothesised that the proof that matter is made entirely of water was provided by his experiment of growing a tree-shoot in a weighed quantity of soil and finding that the weight of the tree increased by over a thousand fold whilst that of the soil decreased only slightly. He failed to consider the contribution of the air.

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FRIEDRICH KEKULE (1829- 96)

1865 – Belgium

portrait of AUGUST STRADONITZ KEKULE &copy:

‘Carbon is tetravalent and is capable of forming ring-type organic molecules’

In the 1860s scientists knew about the molecular formula of benzene, C6H6 , but they did not know how the six atoms are arranged in space. Kekule was the first chemist to suggest that carbon is tetravalent, that is, one carbon atom can combine with four atoms – he saw the possibility that the benzene molecule could be ring-shaped.

diagrammatic representation of the benzene ring showing six linked carbon atomsWikipedia-logo © (link to wikipedia)

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