Atoms of elements in group 16 or group 6A of the periodic table of elements have six valence electrons. Group 16 and group 6A refer to the same elements, known as chalcogens, which are oxygen, sulfur, selenium, tellurium and polonium.
For elements in group 16, the valence electrons are found in the outermost shell of the atom. The exact location can be determined from the electron configuration of the element. For example, the electron configuration for selenium is 1s2 2s2p6 3s2p6d10 4s2p4, and the six valence electrons are found in the 4s and 4p shells. The valence electrons form bonds when atoms join together.