Periodic table still poses puzzles while offering cures for researchers
Scientist who helps develop cures for cancer says not enough is known about some elements
The periodic table - that staple of the chemistry lesson - has 108 elements. They are the basis of the universe and all it contains.
But which of those elements are essential for human life - which ones can't we do without?
"There's a surprising amount that we don't yet know." said Peter Sadler, a professor of chemistry at the University of Warwick in the UK and the Mok Hing-Yiu distinguished visiting professor at the University of Hong Kong.
His work puts him at the point where inorganic chemistry, biology and medicine meet as he mines the periodic table to work out which elements we depend upon and which ones might help us overcome diseases. His expertise is in developing cures for cancer based on precious metals.
"There are about 18 elements that we know are definitely essential for life," said Sadler, who is working on a project at the University of Hong Kong. "These include not only the obvious candidates such as carbon, oxygen, and iron, but also less evident elements including manganese, cobalt and molybdenum."
It's also known that deficiencies of some elements can cause illness. "A lack of iron, or a lack of copper, causes anaemia. A lack of zinc during childhood will mean that the reproductive organs don't develop properly," Sadler says. But there are some elements about which scientists are uncertain.