<Ul> <Li> Blocks (s, p, d, f, ...) </Li> </Ul> <Li> Blocks (s, p, d, f, ...) </Li> <Ul> <Li> <Ul> <Li> Atomic orbitals </Li> <Li> Aufbau principle </Li> </Ul> </Li> </Ul> <Li> <Ul> <Li> Atomic orbitals </Li> <Li> Aufbau principle </Li> </Ul> </Li>

A horizontal row of the periodic table is also known as an atomic