Here's why:
* Orbitals and Energy Levels: Orbitals are regions of space where electrons are likely to be found. They are organized into energy levels (also called electron shells).
* Principal Quantum Number (n): The number of the row in the periodic table corresponds to the principal quantum number (n), which describes the energy level of the electrons in that row.
* Sublevels and Orbitals: Each energy level (n) is further divided into sublevels (s, p, d, and f). The number of sublevels in an energy level is equal to n.
* Orbitals per Sublevel: Each sublevel contains a specific number of orbitals:
* s sublevel: 1 orbital
* p sublevel: 3 orbitals
* d sublevel: 5 orbitals
* f sublevel: 7 orbitals
Therefore:
* The third row (n=3) has 3 sublevels: 3s, 3p, and 3d.
* The 3s sublevel has 1 orbital.
* The 3p sublevel has 3 orbitals.
* The 3d sublevel has 5 orbitals, but these are filled in the fourth row.
In total, the third row has 3 orbitals (1 s orbital and 3 p orbitals).
