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.
elements fill orbitals in order of 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:

According to the Aufbau principle, electrons fill orbitals in order of increasing energy. In the periodic table, moving from left to right across a period, electrons fill orbitals in this increasing - energy order. For example, in period 3, electrons first fill the 3s orbital (lower energy) and then the 3p orbital (higher energy).

Answer:

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