Question

the ________ group has a single electron in the highest occupied energy level.

Answer 1

Alkali Earth Metals, group 1

Answer 2

Of course alkali metals!

"These elements will most likely be in the first period of the periodic table named the Alkali-Metals family."

check this out for reference
http://wiki.answers.com/Q/An_element_with_a_single_electron_in_its_highest_energy_level_is_probably_what_type_of_element

Answer 3

Group 1A also known as alkali metals. For example, Sodium, 11Na it has 11 electrons and it's electronic structure is 2.8.1 the number on the right end of the electronic configuration shows the number of electrons in the outermost shell.