Lesson 2
Science & Chemistry
Anything in black letters = write it in
your notes (‘knowts’)
Why Study Chemistry?
1. Explain the natural world
2. Prepare for a career
3. Be an informed citizen
Science Method of finding out about the world,
based on experiment.
Technology The knowledge and skills available
to a society.
Pure Science Research without a specific application
in mind; “just want to know”
Determining the chemical structure of silk.
Applied Science Research directed toward a practical
goal or application.
Developing a synthetic chemical with silklike properties..
Chemistry Study of the properties and changes
of matter.
Hypothesis A proposed explanation for an observation;
must be testable
Experiment Procedure used to test a hypothesis
Variables Factors that may change in an experiment
Independent Variable Variable changed on purpose; manipulated
Dependent Variable Variable that is observed; responding
Model Represents an object or event; all models
have some flaws.
This is a model of an atom…atoms
are not really like this…but it helps
explain and visualize.
What are some things wrong with
the model of the solar system?
Theory Well-tested explanation; can’t be proven
right, could be proven wrong.
What are some theories you’ve heard of?
Atomic Theory
Cell Theory
Big Bang Theory
Quantum Theory
Theory of Evolution
Theory of Plate Tectonics
Supply & Demand Theory
Global Warming
“Oh… that’s just a theory.”
A theory is not just a hunch…theories are the
best working explanations that we have.
Theories are not guesses, they make
testable predictions that confirm their reality.
Law Fundamental rule that can’t be broken.
What are some scientific laws you’ve heard of?
Laws of Motion
Laws of Thermodynamics
Law of Gravity
Gas Laws (Boyle’s & Charles’s etc)
Antoine Lavoisier (late 1700’s)
Disproved the Phlogiston Theory and explained that
combustion requires oxygen
Realized the importance of
careful mass measurements
in Chemistry
flow-JISS-tunn
Phlogiston Theory – no longer valid!
Some materials burn because they contain phlogiston.
Phlogiston is released into the air when material burns.
When air is full of phlogiston (it is “phlogisticated”) and can no
longer support combustion (flame goes out).
Major flaw…some materials weigh more after they are burnt.
Wood  Ashes + Phlogiston; ashes weigh less…okay…
But…Iron  Rust + Phlogiston; rust weighed more than the iron
Long story short…Lavoisier didn’t like the inconsistencies of the
phlogiston theory and came up with a better explanation (theory)
of combustion and that is how science is supposed to work.
ASSIGNMENT:
Chapter 1 Practice #1
Define these terms…
Hypothesis
Experiment
Theory
Law
Model
Chemistry
True or False…
A well-tested Theory can become a Law.
A Theory can be proven wrong, but can’t be proven right.
Technology has been around long before Science.
The Independent Variable is also called the Responding
Variable.
Explain the difference between…
Theory & Law
Independent & Dependent Variable
Technology & Science