Final answer:
The electron configuration of an atom of an element with atomic number 8 is 1s² 2s² 2p⁶.
Step-by-step explanation:
The electron configuration of an atom of an element with atomic number 8 is 1s² 2s² 2p⁶.
In the periodic table, the atomic number of an element tells you the number of electrons it has. For atomic number 8, which corresponds to the element oxygen, you start filling the orbitals in the order of increasing energy, following the Aufbau principle. The electrons are filled in the 1s, 2s, and 2p orbitals. Therefore, the electron configuration of an oxygen atom is 1s² 2s² 2p⁶.