Quantum Numbers

On Thursday we got some new class notes. We talked about the Quantum Mechanical Model and Quantum Numbers.

The Quantum Mechanical Model describes the electronic structure of the atom as the probability of finding electrons within certain regions of space (orbitals). Remember that in the orbital or "electron cloud" there is only about 90% probability of finding an electron within the orbital. Also, according to Heisenberg's Uncertainty Principle, it is impossible to know both the velocity and position of an electron at the same time.

Some things you should know about Quantum Numbers:

• They are used to specify the "address" of each electron in an atom.



• No atom has the exact same quantum number as another atom, they are all unique (refer to the stadium model in the notes).



• There are four quantum numbers:

Principal Quantum Number (n) which is the most general #. It tells us the energy level and sixe of the orbital. Note: These numbers can only have integral values, and the must be positive.

Angular Momentum Quantum # (l) which tells us the enegry sublevel, type of orbital, and shape of orbital (s, p, d, or f). The value of l has integral values from 0 to n-1, and is related to the shape of the orbital. l=0 is s orbital, l=1 is p orbital, l=2 is d orbital, l=3 is f orbital.

Magnetic Quantum Number (ml) tells us the orientation of the orbital, specifies the exact orbital within each sublevel, and has values between l and -l.

Spin Quantum Number (ms) has an electron spin of either -1/2 or +1/2. An orbital can hold two electrons as long as they are spinning in opposite directions.

That pretty much covers what we learned on Thursday. The next scribe is me again, since I forgot to scribe today.