1. Atoms – The Building Blocks of EVERYTHING
Foothill Chemistry

2. Law of Conservation of Mass

3. Law of Definite Proportions

4. Law of Multiple Proportions
Sample of CO2
Mass of Carbon – 1 g
Mass of Oxygen – 2.66 g
Sample of CO
Mass of Oxygen – 1.33 g
Ratio of Mass of Oxygen in CO2 to Mass of Oxygen in CO – 2:1
Ratios are Small Whole Numbers

5. Dalton’s Atomic Theory
All matter is composed of extremely small particles called atoms.
Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
Atoms cannot be subdivided, created, or destroyed.
Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
In chemical reactions, atoms are combined, separated, or rearranged.

6. Dalton Was Good, but Not Perfect
Isotopes of the Same Atom Differ in Mass
Atoms are Divisible Into Smaller Particles

7. Cathode Ray Tube Experiment

8. Rutherford Experiment

9. Atomic Structure

10. Subatomic Particles
Put it in perspective – If an atom is the size of the Houston Astrodome, the nucleus is a marble on the 50 yard line.

11. Isotope Notation (Element Symbol) 1H 1H 12C 6C 13C 6C 14C 6C
Mass Number
Charge
(Element Symbol)
Atomic Number 1H 1H
12C 6C
13C 6C
14C 6C
Atomic Number = Number of Protons (the element # on the Periodic Table)
Mass Number = Number of Protons + Number of Neutrons
Charge = Number of Protons – Number of Electrons
How Many Protons, Neutrons and Electrons are there in the Isotopes Listed
Above?

12. Atomic Mass Unit Carbon-12 is the basis for the atomic mass unit (amu)
An amu is defined as 1/12 of the mass of a carbon-12 atom
Because there are 6 protons and 6 neutrons, the mass of one proton and one neutron are considered equal (1 amu)

13. Atomic Mass
Weighted average mass of the atoms in a naturally occurring sample of the element

15. Mass, Mass, and More Mass Mass Number – Protons + Neutrons
Atomic Mass Unit – 1/12 of carbon-12 mass
Atomic Mass – Weighted average mass of the atoms in a naturally occurring sample of an element
To be continued with … Molar Mass