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Pure Substances are either:
a) elements
b) Compounds
Are a substance that cannot be separated into simpler substances by physical means
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Elements simplest kind of matter
– http://www.privatehand.com/flash/elements.html?ref=nf
cannot be broken down any simpler and still have properties of that element!
all one kind of atom.
92 naturally occurring elements
Arranged in the Periodic Table of Elements by increasing atomic number
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Symbols & Formulas Elements have a 1 or two letter symbol,
and compounds have a formula.
An element’s first letter always capitalized; if there is a second letter, it is written lowercase.
– Examples: B, Ba, C, Ca, H, He
Some names come from Latin
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made of two or more atoms, chemically combined (not just a physical blend!)
when broken down, the pieces have completely different properties than the original compound.
– Example: NaCl (salt) »Na is explosive and Cl is toxic but
together it is edible
Compounds
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Making Compounds
They must always combine in definite proportions (C12H22O11)
The proportions are determined by the number of chemical bonds that can be formed by each atom.
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Representing Compounds Compounds are represented by chemical
formulas.
– A formula indicates the number and kind of atoms making up a compound.
For example: H2O consists of 2 hydrogen atoms and 1 oxygen atom.
MgSO4 consists of 1 magnesium atom, 1 sulfur atom, and 4 oxygen atoms.
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Separating Compounds Chemical means must be used to
separate compounds
External energy must be used to separate. The energy could be heat or electricity
Example: Electrolysis- electricity is used to split a water molecule to produce hydrogen and oxygen gas.
2H20 ---------> 2H2 + O2
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Identify the Type of Substance
Na
H20
CuCl2
O2
Sn
CO2
FeF3
B
Cobalt
Xenon hexafluoride
Gold
Lithium
Zinc nitrate
Hydrochloric acid
Mercury
krypton
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Compound vs. Mixture
Compound Mixture
Made of one kind of material
Made of more than one kind of material
Made by a chemical change
Made by a physical change
Definite composition
Variable composition
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Classification of Matter