Question

which statement best describes how electrons fill orbitals in the periodic table?
electrons fill orbitals in order of their increasing energy from left to right.
electrons fill orbitals in order of their increasing energy from right to left.
elements fill orbitals in order of increasing energy from top to bottom in each group.
elements fill orbitals in order of increasing energy from bottom to top in each group.

Explanation:

Electrons fill orbitals following the Aufbau principle, which states they fill in order of increasing energy. In the periodic - table layout, this corresponds to filling from left - to - right across periods.

Answer:

Electrons fill orbitals in order of their increasing energy from left to right.