Electron Arrangements Practice Problems

Determine the identity of an element that has completely filled the first, second, and third shells and has three electrons in the fourth shell. Is it a metal or a nonmetal? In which orbital is the last electron found?

The first, second, and third shells and the 4s subshell of an atom are filled. How many electrons are present in the atom? What is the identity of the element?

Determine the group number of bromine. Provide the number of electrons each of its shells holds and the electron configuration in its valence shell.