1. 1.1
What Is Chemistry?
Matter is anything that has mass and occupies space.
Chemistry is the study of the composition of matter and the changes that matter undergoes.
Chemical changes that occur in leaves can cause brilliant displays of color.

2. 1.1
Why Study Chemistry?
What are three general reasons to study chemistry?

3. An Example of a Chemical Reaction
1.1
Why Study Chemistry?
#1 - Explaining the Natural World
An Example of a Chemical Reaction

4. Why Study Chemistry? #2 - Preparing For a Career 1.1
Even after the invention of the digital camera, many photographers still work with film. They use chemical processes to develop film and produce prints in a darkroom. Inferring Why isn’t film developed under natural light conditions?

5. Why Study Chemistry? #3 - Being an Informed Citizen 1.1
By registering to vote, these citizens in Chicago, Illinois, can have a say in the decisions made by their government. Those decisions include how much money to provide for scientific research.

6. Organization of Matter
The flow chart summarizes the process for classifying matter. Any sample of matter is either an element, a compound, or a mixture. Interpreting Diagrams What is the key difference between a substance and a solution?

7. Looking at the History of the Atom
Classification of Matter Practice w/ whiteboards
Introduction to Atoms
Looking at the History of the Atom

8. History of Atom All atoms share the same basic structure
During past 200 years, scientists have proposed different models

9. Dalton’s Model
All matter is composed of tiny, indivisible particles called atoms
Atoms of each element are exactly alike
Atoms of different elements have different masses
Atoms of different elements can join to form compounds

10. Dalton’s Model

11. Thomson’s Model End of 1800s
Thomson discovered that atoms were not simple, solid spheres
Atoms contained subatomic particles
Very small, negatively charged
Called them ELECTRONS

12. Thomson’s Model Also knew that atoms were electrically neutral
Must contain enough positive charge to balance negative charge of electrons
Developed model where electrons were stuck into a positively charged sphere
Like chocolate chips in cookie dough

13. Thomson’s Model

14. Rutherford’s Model
By early 1900s, scientists knew that positive charge of atom comes from subatomic particles called PROTONS
1911—Rutherford begins to test theory
His experiments led him to believe that protons are concentrated in a small area at center of atom
Called this area the NUCLEUS

15. Rutherford’s Model
Rutherford’s model describes an atom as mostly empty space, with a center NUCLEUS that contains nearly all the mass
Like the pit in a peach
Contained the PROTONS (+)

16. Bohr’s Model Modified Rutherford’s model in 1913
Proposed that each electron has a certain amount of energy
Helped electron move around nucleus
Electrons move around nucleus in region called energy levels
Energy levels surround nucleus in rings, like layers of onion

17. Bohr’s Model Has been called planetary model
Energy levels occupied by electrons are like orbits of planets at different distances from the sun (nucleus)

18. Electron Cloud Model Model accepted today
Electrons dart around in an energy level
Rapid, random motion creates a “cloud” of negative charge around nucleus
Electron cloud gives atom its size and shape

19. Electron Cloud Model

20. FOCUS ON ELEMENTS Simplest form of matter
Unique set of chemical & physical properties
Identified by number of protons

21. Atomic Number Number of protons Symbol is “Z”
Found on periodic table (check the legend)
Elements are different because they contain different numbers of protons
Protons found in dense nucleus
HMMM – How do protons stay “TOGETHER” in the nucleus if they are all positive?

22. Practice Finding Number of Protons
Aluminum
Bromine
Carbon
Potassium
Tungsten

23. Mass Number Number of protons + number of neutrons Symbol is “A”
4.3
Mass Number
Number of protons + number of neutrons
Symbol is “A”
NOT found on periodic table
Neutrons found in dense nucleus

24. How Many Electrons Do you Have?
4.3
How Many Electrons Do you Have?
Neutral (no charge) electrons = protons
Positive charge subtract electrons
Negative add electrons

25. Practice Counting Subatomic Particles in IONS
(atoms with a charge)
Mass Number
# Protons
# Neutrons
# Electrons
Al3+ 27
O2- 16
Cu2+ 64 Ca 40
Ca2+

26. Isotopes How are these atoms alike? How are they different? 4.3
Neon-20, neon-21, and neon-22 are three isotopes of neon, a gaseous element used in lighted signs. Comparing and Contrasting How are these isotopes different? How are they similar?

27. Isotopes Same element Same number of protons Change number of neutrons
4.3
Isotopes
Same element
Same number of protons
Change number of neutrons
Different Mass Numbers

28. Draw a model of each of the atoms listed.
Chromium-58
Chromium-63
# of protons
# of neutrons
# of electrons
Nitrogen-15
Nitrogen-20
# of protons
# of neutrons
# of electrons