1. Composition of Matter Atomic theory – the beginnings
November 2nd, 2006
Composition of Matter
Atomic theory – the beginnings

2. Drill When you compare atoms and compounds to the English language:
elements are like __________
Compounds are like __________
Atoms are the smallest example of __________
Molecules are the smallest example of __________

3. How Chemists Figured out Atomic Theory
Hypothesis (Hø)
A prediction
It’s possible to test it
Explains observations
* Scientific Law
A fact of nature
NOT an explanation
BUT can be used as proof of an explanation
2. Theory
An explanation
Many observations support it

4. Hypothesis
If I study and do my homework I will do well in Ms. Pallandre’s chemistry class
You can test what the effect will be of studying and doing homework (indep. vars.)
Dep. var. = grade
Observation would be the grade & study habits

5. Theory Students that do well in school have good study habits
People who study education have written papers saying this
An explanation of why students do well

6. Chemistry History
Saw that when elements were combined to form compounds, the ratios that were used up were whole numbers.
John Dalton

7. JOHN DALTON’s
ATOMIC THEORY
What he was
right about &
wrong about
5 MAIN POINTS

8. Dalton’s atomic theory
Elements are made of tiny particles called atoms
All atoms of a given element are identical
The atoms of a given element are different from those of any other element

9. Dalton’s atomic theory
Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers of types of atoms.
Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process. A chemical reaction simply changes the way atoms are grouped together.