Thorium —
Photo Credit:

Marie Curie, c. 1920 —
Photo Credit: By Henri Manuel - Public Domain, https://commons.wikimedia.org/w/index.php?curid=32735756

Marguerite Catherine Perey —
Photo Credit: By Source, Fair use, https://en.wikipedia.org/w/index.php?curid=38939348

Francium —
Photo Credit:

Caesium —
Photo Credit:

Gustav Kirchhoff (left) and Robert Bunsen (right) —
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=6890735

Bunsen burner —
Photo Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=279064

The Old University Marburg — Houses the university church, the department for religious studies and a representative lecture hall
Photo Credit: By Hydro - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=26232281

logo of University of Marburg —
Photo Credit: Own work based on: Uni Marburg Logo.svg:http://www.uni-marburg.de, CC0, https://commons.wikimedia.org/w/index.php?curid=98325161

Robert Wilhelm Bunsen —
Photo Credit: By Universitätsbibliothek Heidelberg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=66708606

Kirchhoff, Bunsen, Roscoe — Gustav Kirchhoff (left) and Robert Bunsen (center) discovered rubidium by spectroscopy. (Henry Enfield Roscoe is on the right side.)
Photo Credit: By Henry Roscoe - Public Domain, https://commons.wikimedia.org/w/index.php?curid=3534447