1. Chapter 3
Brian, Eric, Harry, Rafi

2. Key Concepts: 3.1
Section 1
Dalton's Atomic Theory: 1.) All matter is composed if extremely small particles, 2.) Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties, 3.) Atoms cannot be subdivided, created, or destroyed, 4.) Atoms of different elements combine in simple whole-number ratios to form chemical compounds, 5.) In chemical reactions, atoms are combined, separated, or rearranged...
Modern Atomic Theory: -atoms are divisable into even smaller particles (protons, neutrons, electrons, quarks)

3. Key Concepts: 3.2
Section 2
While investigating the outcome of the cathode ray tube tests, scientists noticed that the current passing through the cathode-ray tube to the surface directly opposite, the cathode glowed. They hypothesized that the glow came from a stream of poarticles.
-Cathode rays were deflected by a magnetic field in the same manner as a wire carrying electric current, known to be negatively charged
-the rays were deflected away from a negatively charged object
Atomic Nucleus experiment; Ernest Rutherford and his associates sent fast moving alpha particles at a piece of gold foil. The particles were positively charged and 1 in 8000 of the particles were deflected. This meant that the particles were deflected by a very small, positively charged nucleus in the atom. 
Electron: negatively charged; mass number 0
Proton: positively charged; mass number 1
Neutron: neutral charge; mass number 1

4. Key Concepts: 3.3 See Vocabulary and Sample Problems
"Although Isotopes have different masses, they do not differ significantly in their chemical behavior"
-atomic number
-mass number
-isotopes
-atomic mass unit
-average atomic mass
-mole
-avagadro's number
-molar mass

5. Chapter 3 Vocabulary
The law of conservation of mass- A law that states that mass is neither destroyed nor created during ordinary chemical reactions or physical changes.
The law of definite proportions- A law that states that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.
The law of multiple proportions- a law that states that if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.

6. Vocabulary (continued)
Atom-The smallest particle of an element that retains the chemical properties of that element
Nucleus- A very small region located near the center of an atom.
        -Proton- a positively charged particle located inside of the nucleus
        -Neutron- a neutral particle located inside of the nucleus
        -Electron- Negatively charged particles in a region surrounding the nucleus.
Nuclear Forces- short-range proton-neutron, proton-proton, and neutron-neutron forces that hold the nuclear particles together
Isotopes- atoms of the same element that have different masses.
Nuclide- a general term for any isotope of any element.

7. Important Numbers and Equations
Atomic Number- the number of protons in the nucleus of each atom of that atom
Mass Number- the total number of protons and neutrons in the nucleus of an isotope
Mole - the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon -12.
Avogadro's Number  x 10^23 -- the number of particles in exactly one mole of a pure substance

8. Problems! Yay!
1. What were the five points of Dalton's atomic theory, and which ones have been proven false?
a) All matter is made up of tiny particles called atoms.    True
b) Atoms of a given element are identical in size, mass, and other   False proportions. Atoms of different elements differ in all these properties.         
c) Atoms cannot be subdivided, created or destroyed.    False
d) Atoms of different elements combine in simple 
whole number ratios to form chemical compounds.        True
e) In chemical reactions, atoms are 
combined, separated, or rearranged.                True

9. More Problems! Extra yay!
What is Avogadro's number? What does it measure?
Approximately X 10^23
It is the number of particles in a mole
Who discovered the electron, and how?
J. J. Thompson discovered it when he placed a paddle wheel inside a cathode ray tube. The cathode ray was then repelled from the negative end of the tube. The ray pushed the paddle wheel on its way, showing that the ray had mass.

10. Guess what this slide is for!
Who discovered the atomic nucleus, and how?
Ernest Rutherford. He shot positively charged alpha particles at a sheet of gold foiil. Most of them passed through, but a very small percentage deflected almost 180 degrees. He reasoned that there had to be a single point of high positive charge for such a repulsion to occur.
What is the law of multiple proportions?
    
A law that states that if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.

11. Just one guess!
What are the laws of conservation of mass and definite proportions?
The law of conservation of mass- A law that states that mass is neither destroyed nor created during ordinary chemical reactions or physical changes.
The law of definite proportions- A law that states that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.