[jakeo7]

I am doing a school project and i need to know
"Why did it take scientists so long to discover Francium"

[madscientist]

Have a look at these websites, they should help.

http://en.wikipedia.org/wiki/Francium

http://www.webelements.com/webelements/elements/text/Fr/key.html

The longest lived isotope, 223Fr, a daughter of 227Ac, has a half-life of 22 minutes. This is the only isotope of francium occurring in nature, but at most there is only 20-30 g of the element present in the earth's crust at any one time. No weighable quantity of the element has been prepared or isolated. There are about 20 known isotopes.

(webelements)

Its a wonder it is even known looking at that statement, amazing 

[jakeo7]

Those websites give me some good information on francium but they dont answer my question

[AWK]

Those websites give me some good information on francium but they dont answer my question

Do you think recognizing 30 g of unstable element disperged in the crust is an easy task?