atomic structure psc chapter 3. atomic theory of matter evidence of atoms law of definite...
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Atomic Structure
PSC Chapter 3
Atomic Theory of Matter
Evidence of atoms Law of Definite Proportions Law of Conservation of Mass Law of Multiple Proportions Dalton’s Atomic Theory
Evidence of atoms
400 BC – Greeks Atomic Theory-Democritus
all matter is composed of small particles called atoms Atomos - indivisible
18th Century Europe– Experimental results support the existence of atoms
Basic Components of the Theory…
Law of Definite Proportions– For any sample, a compound always has the same
composition A given compound contains the same elems. in the same
proportions by mass
– For example: NaCl is always 39.34% Na and 60.66% Cl by mass
Basic Components of the Theory…
Law of Conservation of Mass– For any chemical reaction, the mass of the products
equals the mass of the reactants. Matter is neither created nor destroyed.
– For example: 32.07 amu of S combines with 32.00 amu of O2, 64.07 amu
of sulfur dioxide.
Basic Components of the Theory…
Law of Multiple Proportions– For any compounds formed by the same two
elements, the mass ratio of one of the elems. that combines w/ a fixed mass of another elem. can be expressed in small whole numbers
– For example: H2O and H2O2
Dalton’s Atomic Theory
1. All matter is made of indivisible & indestructible atoms.
2. All atoms of the same element are identical in their physical and chemical properties.
3. Atoms of different elements differ in their physical & chemical properties
Dalton’s Atomic Theory
4. When atoms combine, they unite in simple, whole-number ratios to form compounds.
5. Chemical reactions consist of the combination, separation, or rearrangement of atoms.
Assignment
Do Page 78 #1-9
Be ready for the quiz next time!