1. Table of Contents (UPDATE)
Topic
Date
Page Numbers
Unit 1 Study Guide
9/18-19/2014 23
Unit 1 Mastery Tracker
9/22-23/2014 24
History of the Atomic Theory
25-28
Structure of the Atom
9/24-25/2014
29-32

2. The History of the Atomic Theory

3. GUIDED NOTES
The guided notes you have been given have less information filled provided for you.
It is up to you as the student to take accurate notes during todays class.
If you miss something in the presentation you can always go to the class website to complete taking your notes.

4. Theory v. Law Scientific Theory
Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing
If enough evidence exists, it becomes accepted as a valid explanation of a phenomenon.
Theories are foundations for furthering scientific knowledge and for putting the information gathered to practical use. Scientists use theories to develop inventions or find a cure for a disease.

5. Theory v. Law Scientific Law
Is a description of an observed phenomenon, not an explanation for what was observed.
For example, Kepler's Laws of Planetary Motion, describe the motions of planets but do not provide an explanation for their movements.
In chemistry, laws are often expressed only as an equation.
Laws are usually proven, but can be refuted (rarely).

6. “Atomos”
Atom – smallest particle that retains the properties of an element.
Atom – comes from the Greek word “atomos” meaning “no cut” or “indivisible.”
Throughout the years, scientists have drastically changed what they think an atom look like.

7. The Earliest Theory of the Atom
5th Century BC
Leucippus and Democritus – develop the belief that everything is made up of tiny parts called atoms.
The Earliest Model

8. …and people actually believed him… [straight face]
But…
Aristotle disagreed with Leu and Demo, the idea of the atom disappeared for the next 2000 years.
…and people actually believed him… [straight face]
I hereby solemnly decree the atoms do not exist in this world
-Aristotle

9. John Dalton What: Created the atomic theory
defining what an atom looks like.
When: 1803
Key Points
Dalton is called the “father of the modern atomic theory”
John Dalton performs experiments which show elements do consist of tiny atoms

10. Dalton’s Postulates (Theories)
Elements are made of tiny particles called atoms.
All atoms are identical in composition
The atoms of a specific element are different from those of any other element.
Atoms can combine to make compounds
Atoms cannot be created or destroyed.

11. J. J. Thompson What: Discovered the electron and charge When: 1897
Key Points
Discovered the electron using a cathode ray tube experiment
Developed the plum pudding model

12. Let’s All Go to the Movies…
Now, let’s take a look at what J.J Thompson was trying to describe 

13. Ernest Rutherford What: Discovery of the Nucleus When: 1911 Key Points
Gold Foil Experiment
Shot radioactive alpha particles at a sheet of gold foil, expected them to go through the foil
Some particles went through, some shot off at angles and some came straight back
Experiment made him predict a positively charged nucleus off which the particles deflected

14. Gold Foil Experiment

15. Expected
Results
Actual
Results

16. Niels Bohr What: Electron Orbits and Bohr Model When: 1922 Key Points
Electrons move around the nucleus in certain paths or energy levels
Each distance corresponds to a certain quantity of energy that an electron can have.

17. Electron Orbits
Models:

18. Shrodinger What: Discovered the Quantum Model When: 1930 Key Points
Model shows that electrons do not have a planetary orbit they exist in an electron cloud.
Electrons can be thought of as waves instead of particles

19. Current Atomic Theory Currently the theory tells us that:
Atoms are made of smaller particles called protons, neutrons and electrons (and these are made of even smaller particles – quarks!)
Electrons don’t travel in definite paths
The exact path of electron cannot be predicted.
Orbitals are regions where electrons are likely to be found. They are also known as electron clouds.

20. Let’s Sum it All Up Categories Indivisible Electron Nucleus Orbit
Electron Cloud
Greek X
Dalton
Thomson
Rutherford
Bohr
Current Atomic Theory

21. Independent Practice Page 27
Work on the Worksheet you have been given by your teacher. ASK 3 BEFORE ME RULE IS IN EFFECT

22. Timeline Project Document
Home Learning (Poster Board) A-Day Due: September 26th B-Day Due: September 29th
Create a timeline of atomic theory beginning with Leucippus and Democritus and ending with our current model.
Use you’re the internet, text books and notes to add details to each contribution.
Each contribution should have:
Date or time period
2-3 facts
Picture of important figure (scientist) or model
Timeline Project Document

23. Structure of the Atom

24. WHAT IS AN ATOM MADE OF?
An atom is the smallest particle of matter. It cannot be created or destroyed by chemical means.
Subatomic Particles
Protons
Neutrons
Electrons

25. Subatomic Particles Proton (p+)
Subatomic particles present in the nucleus with positive charge
Electron (e-)
The negatively charged particles with revolves around the nucleus
Neutron (n0)
A particle with no charge (neither positive nor negative) that is present in the nucleus. It appears in the nucleus of all atoms except hydrogen

26. Element Anatomy

27. Subatomic Particles Information
Charge
Mass #
Location
Electron -1
Electron cloud
Proton +1 1
Nucleus
Neutron

28. Atomic Number
Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element.
Element
# of protons
Atomic # (Z)
Carbon 6
Phosphorus 15
Gold 79

29. Mass Number Mass # = p+ + n0
Mass number is the number of protons and neutrons in the nucleus of an isotope.
Mass # = p+ + n0 p+ n0 e-
Mass #
Oxygen - 10 - 33 42
- 31 15 18 8 8 18
Arsenic 75 33 75
Phosphorus 16 15 31

30. Isotopes
atoms of the same element having different masses due to varying numbers of neutrons.
Isotope
Protons
Electrons
Neutrons
Nucleus
Hydrogen–1
(protium) 1
Hydrogen-2
(deuterium)
Hydrogen-3
(tritium) 2

31. Composition of the nucleus
Atomic Masses
Atomic mass is the average of all the naturally occurring isotopes of that element.
Isotope
Symbol
Composition of the nucleus
% in nature
Carbon-12
12C
6 protons
6 neutrons
98.89%
Carbon-13
13C
7 neutrons
1.11%
Carbon-14
14C
8 neutrons
<0.01%
Carbon =

32. Independent Practice