Thallium was used as a poison in the Agatha Christie mystery…

Thallium was used as a poison in the Agatha Christie mystery story “The Pale Horse.” Thallium has two possible cationic forms, +1 and +3. The +1 compounds are the more stable. Write the electron configuration of the +1 cation of thallium. Note: write configuration in the following form. 1s22s22p63s2