1. The Atom
From 400 BC to now

2. The Atom
Who are some famous people that helped develop the theory of the atom?
Democritus
Dalton
Thomson
Rutherford
Bohr
Schrodinger/Hiesenberg

3. The Atom What did Millikan do?
Millikan found the charge of an electron.
It is x Coulombs.
He then found that the mass was 1/1840 x that of a proton.

4. The Atom What are the parts of an atom? Proton, +, nucleus
Electron, -, electron cloud
Neutron, 0, nucleus

5. The Atom What are isotopes?
Isotopes contain different numbers of neutrons, but have equal protons.
Equal protons makes them the same element.
Neutron differences give them different properties.

6. The Atom How do we find Isotope abundances?
Abundances are found by using % of each isotope involved.
Example: Boron has 80.2% boron-11, and 19.8% boron-10. What is the atomic mass?
10.8 AMU

7. The Atom What happens to unstable nuclei? Unstable nuclei decay.
Alpha radiation.
Beta radiation.
Gamma radiation.
We will talk about others later.

8. The Atom What do we know about electrons? They surround the nucleus.
They are free to move from atom to atom.
They determine the characteristics of an atom
They form bonds.
They determine the ions formed.
They fill orbitals.

9. The Atom Who are some people associated with electrons in atoms?
Planck
Bohr
de Broglie
Heisenberg
Schrodinger

10. Energy levels What are they? 1, 2, 3, 4, 5 . . .
Each one represents another “shell” on an atom
Each one has an increasing number of sublevels

11. Sublevels What are they? S, P, D and F What does each one hold?
S orbital: 2 electrons of opposite spin (1 orbital)
3 P orbitals: 6 electrons of 3 clockwise 3 counterclockwise spin (3 orbitals)
5 D orbitals: 10 electrons of 5 clockwise and 5 counterclockwise spin (5 orbitals)
7 F orbitals: 14 electrons of 7 clockwise and 7 counterclockwise spin (7 orbitals)

12. S P D and F orbitals

13. Examples What is the outer orbital in Helium?
What orbital is filling in Nitrogen?
What orbital is the outside of Copper?
What is the outside of Europium?

14. Drawing orbital filling
Draw Aresenic.
How do we use the shortcut?
You can skip up to the Nobel Gas right before your element.

15. Pauli exclusion principle
What does it say?
An atomic orbital may only hold 2 electrons at one time.
Each electron has to have a different spin (clockwise or counterclockwise).

16. Electron orbital filling
What determines their order?
The aufbau principle states that electrons occupy the orbitals of lowest energy first.
How do we find this order?

17. Spin rules What determines the spin of the electron? Hund’s rule.
This rule states that electrons fill the orbitals in a way that gives the atom the largest number of electrons with the same spin.
What does this mean?

18. Stability What adds to the stability of the atom?
Not all atoms follow the aufbau principle.
Cr and Cu