Final answer:
The electron configuration of the elements in the third period follows a specific pattern of filling orbitals based on the distribution for the first 10 elements. The order of filling orbitals can be easily predicted by following the arrows on the diagonal of the periodic table.
Step-by-step explanation:
The electron configuration of the elements in the third period can be determined by following the pattern of filling the orbitals based on the given distribution for the first 10 elements. The 4s orbital fills with two electrons, and then the next 10 electrons are placed in the 3d orbital. The electron configuration of phosphorus (P), for example, is [Ne]3s²3p³. The order of filling orbitals in general can be predicted by following the arrows on the diagonal of the periodic table.