What is the electron configuration for francium?

Hint: The elements in the periodic table are arranged according to the atomic number. The atomic number is equal to the number of electrons in any atom. The electronic configuration consists of the filling of these electrons into the orbital. The filling of electrons is through Aufbau principle that tells the electron configuration of elements.

Complete answer:
The electronic configuration of any element is the representation of the total number of electrons in that atom which is equal to the atomic number of that element. Electronic configuration of any element consists of filling the atomic orbital with electrons. The filling of electrons in various orbits is according to a principle of Aufbau that takes place from the lower energy level to the higher energy level. The filling takes place in s, p, d, and f subshells. These subshells are written along with the number of shells, like 1, 2, 3, etc.
We have been given francium that is denoted by the symbol Fr. It is an element of the group 1 of the periodic table, so it consists of the outer shell configuration as$n{{s}^{1}}$. According to the periodic table, francium has an atomic number of 87. So, the configuration will be:
Fr = 87, $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{10}}4{{s}^{2}}4{{p}^{6}}4{{d}^{10}}5{{s}^{2}}5{{p}^{6}}4{{f}^{14}}5{{d}^{10}}6{{s}^{2}}6{{p}^{6}}7{{s}^{1}}$
This configuration when rounded to the nearest noble gas, Radon, Rn having 86 atomic number, the configuration becomes, Fr = $[Rn]7{{s}^{1}}$
Hence, the electron configuration for francium is $[Rn]7{{s}^{1}}$.

Note:
The diagrammatic representation of the Aufbau diagram is as follows
The arrows denote the order of the filling of electrons. s orbital can accommodate 2 electrons, p can have 6, d can have 10, while f can have 14 electrons filled. The shorthand configuration of atoms consist of a noble gas written to cover the noble gas configuration, and then the rest of the configuration is written.