How many valence electrons does francium have?

Francium has one valence electron as a member of the alkali metal group on the periodic table of elements. That valence electron is in the s-orbital of the seventh energy level.

The full electron configuration for francium is notated as 1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10 6s2p6 7s1, which can be simplified to [Rn] 7s1. In ascending order, the configuration indicates that francium carries one, two, eight, 18, 32 and 18 electrons in each energy level. One atom of francium has 87 electrons, balanced by 87 protons, as indicated by the element's atomic number. Francium is abbreviated by the symbol Fr.