1. Chapter 5 electrons in atoms

2. Modern model of atom – Rutherford’s model was incomplete….
Quantum Theory – modern, math description, of the behavior of electrons in atoms.
*it estimates the probability of finding an electron in a certain position

3. Numbers used to describe an e- 1. energy level 2. location
Quantum numbers -
Numbers used to describe an e-
1. energy level
2. location
3. Shape of orbital (*an orbital is an electron cloud & has 2 e-s)
4. orientation of orbitals
5. spins of e-s in orbitals

4. Quantum numbers:
1) Principle quantum number – (n) main energy level occupied by the electron; the distance of an orbital to the nucleus. ex/ n= 1, n=2 (whole numbers) 2) Angular momentum quantum number (l) indicates shape of orbital: s – sphere shape (2 e-) p – dumbbell shape (6e-) d – double dumbbell (10 e-) f – complex shape (14 e-)

5. 3) Magnetic quantum number (m) orientation of orbital (x, y, z) 4) Spin Quantum number has two possible values +1/2 or -1/2

6. Electron Configurations - the ways in which electrons are arranged around the nucleus of an atom.
Apply three rules: (use Diagonal rule see pg. 135)
Aufbau principle – electrons enter orbital of lowest energy first (*start at 1s)
Pauli exclusion principle – two electrons of opposite spin occupy an orbital (no two electrons in the atom can have the same set of quantum numbers)

7. 3 Rules continued….
3) Hund’s Rule – When electrons occupy orbitals of equal energy, electrons fill the orbitals one at a time and then will pair up.
Write the electron configuration for the following elements: (use pg. 135 or draw diagonal rule)
a) H b) B c) C d) Fe e) Zn
Draw orbital diagrams for the same elements above.

8. Noble gas notation
Noble gas notation is a short hand notation for writing the electron configuration by using the nearest noble gas atom to represent the stable inner core electrons.
The noble gas is denoted with brackets: like this [Ne]
Write the noble gas notation for sodium
Selenium?

9. Sec 1
For electromagnetic radiation, c (speed of light) equals _________________________.
A quantum of electromagnetic energy is called _______________.
The energy of a photon is related to its _____________.
If electrons in an atom have the lowest possible energies, the atom is in the ________________.
Bohr’s theory helped explain why excited hydrogen gas gives off certain ___________ of light.
According to Bohr’s theory, an excited atom would _______________ energy.

10. Section 2 Review Q’s
A three-dimensional region around a nucleus where an electron may be found is called a(n) ____________.
Unlike in an orbit, in an orbital an electron’s position cannot be known _______________.
What are the 4 quantum numbers and what do they represent?
What are the shapes of the orbitals?
How many electrons fit in each orbital?
What is the difference between a 2s orbital and a 4s orbital?

11. Sec 2
How many orbital shapes are possible at the 2nd energy level? 3rd energy level?
An electron for which n= 5 has more _____ than an electron for which n=3.
If 8 electrons completely fill a main energy level, what is n?

12. Section 3 Review Q’s Draw the diagonal rule. What does this rule show?
Know the 3 rules for writing electron configurtions.
Write the electron configuration for Si.
Draw the orbital diagram for Mg.
What element has the following configuration: 1s22s22p63s1 ?
How many electrons in the highest energy level of a bromine atom?
Which element has the electron configuration of [Ar]4s23d104p5