An atom has 2 electrons in the first electron shell and 3 electrons in the second electron shell. How is this expressed in electronic configuration notation?
An atom has 6 electrons: 2 in the first electron shell and 4 in the second electron shell. It is excited, and one electron moves from the second electron shell to the third electron shell. What is the electronic configuration of the atom?
Determine the electron configuration of a helium atom by listing the occupancy of the electron shells, in order of increasing energy.