1. 5.2 QUANTUM THEORY AND THE ATOM PART THREE Quantum numbers and orbitals

2. Review: in Bohr’s atomic model, electrons orbited the nucleus as shown below. To mathematically describe the orbit of an electron, Bohr used one quantum number, n = 1, 2, 3 ……which designated 2 things: The orbit for n = 1 is CLOSEST TO MOST FAR FROM the nucleus, and is HIGHEST LOWEST in energy Bohr’s orbits were all _____________________ in shape.

3. In quantum theory, electrons may be found in atomic orbitals. The book says an orbital is: “a 3-D region around the nucleus that describes the probable location of an electron.” in other words: each orbital can contain ____, ____, or ____ electrons (how many?)

4. Quantum mechanics has ______________ quantum numbers to describe the arrangement of electrons. The first quantum number is known as the and is very similar to Bohr’s. It is n = 1, 2, 3 …… and describes roughly the same things as Bohr’s quantum number, n.

5. In quantum mechanics, the principal, the second, and the third quantum numbers together describe the of an electron; i.e., the area of space that the electron has a________% probability of being found in; The fourth quantum number describes a particular electron in that orbital (actually the spin of the electron.)

6. QUANTUM # SPECIFIESDESCRIBES FOR AN ORBITAL… Principal: quantum # n = 1, 2, 3…. Second quantum # Third Quantum #

7. Bohr’s orbits were all _____________ in shape. In quantum mechanics, each orbital has one of ______________ different possible shapes. A sublevel contains ______________________ orbitals, depending on the shape of the orbitals All of the orbitals in a particular sublevel have THE SAME DIFFERENT shape(s)

8. s orbitals are shaped like a sphere. How many orbitals can there be in one s-sublevel?

9. p orbitals are shaped like a figure-8. There are 3 in any one p-sublevel. Each one has a different orientation in space

10. d-orbitals are mostly shaped like 2 figure-8’s together. There are 5 of them in any one d-sublevel.

11. Here are f orbitals. Any one sublevel can contain 7 f orbitals

12. The orbitals have differing amounts of energy. For orbitals in the same principle energy level: s < p < d < f Look at the shapes – does this make sense?

13. The Aufbau Principle states that: each electron occupies the lowest energy orbital available. Does this make sense?

14. With this basic knowledge of quantum numbers and orbitals, we can now begin to develop a picture of the atom and to write electron configurations; this is a very important skill in chemistry. Based on the electron configuration of each element, we can explain and predict the behavior of that element.