1. Electrons
If all atoms are composed of the same fundamental building blocks, how is it that different atoms have vastly different chemically behaviors?

2. Bohr Model Only specific energy level values are allowed.
Quantization of energy
Energy is gained and lost when transitions occur.
See it: Bohr/applet_files/Bohr.html

3. Structure of the atom 3 subatomic particles: Atomic number (Z)
proton (p+)
neutron (n0)
electron (e-)
Atomic number (Z)
Number of electrons?
Isotopes
Atomic mass

4. What does an atom look like?

5. The best model – Electron Orbitals
Orbital: 3-D area in space where you are 90 % likely of finding an electron.
These areas are defined by a wavefunction equation.
2 electrons maximum can fit in an orbital.

6. These probable locations are called orbitals.
Electron energies and locations are best described with math formulas called wavefunctions.
When graphed, the solutions to these formulas describe “probable locations” of the electrons.
These probable locations are called orbitals.
Video
sometimes called “electron clouds”
What does it mean?

7. Wavefunction graphs
3-D graphs show “probability densities” for electrons in different orbitals.
Quantum theory can only specify location 90% of the time.

8. Orbital Shapes s sublevels have spherical orbitals.
p sublevels have dumb-bell orbitals.

9. More Shapes
d sublevels have clover-leaf orbitals.

10. Energy Levels, Sublevels and Orbitals
Each orbital is assigned to a level and a sublevel.
As orbitals occupy higher energy levels, the orbital size gets bigger (so that its area is further from the nucleus) 2s

11. Energy Levels, Sublevels and Orbitals
Energy order of first 16 sublevels:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s
energy level sublevel (shape)
The larger the number, the further the orbital is from the nucleus.
How many orbitals are there in each sublevel?

12. When is a sublevel filled?
Sublevels available
Maximum # of electrons
in level 1 s 2 3 4

13. When is a sublevel filled?
Sublevels available
Maximum # of electrons
in level 1 s 2
s, p 8 3
s, p, d 18 4
s, p, d, f 32

14. What does an electron configuration “look like?”
Sodium atoms have 11 electrons:
1s2 2s2 2p6 3s1
What does aluminum look like?
What would Aluminum look like? e- e- e- e- e- e- e- e- e- e- e-

15. Electron Configurations
No need to memorize the order of levels and sublevels! Use the PT!

16. Noble Gas Shortcut Ex: Magnesium: [Ne] 3s2 Bromine: [Ar] 4s2 3d10 4p5
Are all of an atom’s electrons involved in chemical bonding?
Electron configurations can be “shortened” to emphasize the valence electrons with the Noble Gas Shortcut.
Ex: Magnesium: [Ne] 3s2
Bromine: [Ar] 4s2 3d10 4p5

17. Valence electrons Don’t forget to count s and p electrons as valence!
Only the electrons located away from the nucleus are used in making a chemical bond.
Valence electrons: electrons found in the highest energy level of an atom.
8 valence electrons maximum.
Noble gas shortcut emphasizes an element’s valence electrons.
Don’t forget to count s and p electrons as valence!

18. Orbital Diagrams 3 rules: Aufbau, Hund, Pauli
Each box represents an orbital.
Arrows represent electrons.
3 rules: Aufbau, Hund, Pauli

19. Predicting Charge In general, which elements are these?
Octet rule: Atoms gain or lose electrons to achieve a filled outer
energy level of electrons. (look like a noble gas)
This is most often 8 electrons in the outer energy level.
General rules: Atoms with 3 or fewer valence e- lose those electrons, forming a positive ion, or cation.
In general, which elements are these?
Atoms with 5 or more valence e- gain electrons, forming a negative ion, or anion.
In general, which elements are these?

20. Cations
Positively charged ions
Result from loss of valence electrons.
Ex: Magnesium: [Ne] 3s2 will lose its 2 valence electrons, to result in Mg2+ ion.
Cations achieve noble-gas or pseudo noble gas electron configuration.
Named _____________ ion.
insert element name

21. Anions
Negatively charged ions
Result from gain of valence electrons from another atom.
Ex: Nitrogen: 1s22s22p3 will gain 3 valence electrons from another atom, to result in N3- ion.
Anions achieve noble-gas electron configuration.
Named ____________ -ide
insert element name, dropping last syllable

22. Polyatomic ions
Primarily negatively charged ions, but there are some positive ones.
They are molecules that carry a charge.
The back of your PT lists the ones used in this course.
Their names end in –ate or –ite for the most part.