The four quantum numbers are n, l and ml, and ms.
The first three of them describe the orbital on which the electron of an atom is.
n is the main quantum number and it represents the shell. This is also the row (period) on the periodic table.
l is the orbital angular momentum number and it tells the shape of the orbital. It may be
0 which is s orbital
1 is p orbital
2 is d orbital
3 is f orbital
ml is the the magnetic quantum number: It gives the position of the orbital in the space.
Those three quantum numbers, n, l, and ml, then, determine the orbital.
The fourth quantum number, ms, is the spin.
Answer: the two electrons with the same n, l, and ml quantum numbers are said to be in the same orbital.
