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combs
Week3Presentation.pptxCOMPOSITIONAL
FORMS
OF
MATTER
- all matter can be divided into three compositional classes
Elements
Compounds
Mixtures
A. Elements
- the basic units of all matter
- the building blocks
- you would no longer have an element
- elements cannot be broken down (or decomposed) chemically
To avoid writing out the entire name every time an element was used a “chemical shorthand” was developed
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-there is one assigned to each element
each element is given a symbol known as the “Atomic Symbol”
also known as an abbreviated expression for an element
- usually an abbreviation of their names
-generally symbols are taken from the first letter of the name
-others must have two letters to distinguish them
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Carbon and Chlorine
C and Cl
-- 1st letter always capitalized
-- 2nd letter always in lower case
-some are taken from their Latin names
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Fe for Iron
Latin—Ferrum
K for Potassium
Latin—Kalium
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LIST OF
REQUIRED ELEMENTS
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Aluminum Al
Bromine Br
Calcium Ca
Carbon C
Chlorine Cl
Copper Cu
Hydrogen H
Iodine I
Iron Fe
Magnesium Mg
Mercury Hg
Nitrogen N
Oxygen O
Phosphorus P
Platinum Pt
Sodium Na
Sulfur S
Elements are divided into 2 general groups
1)
2)
Metals
Non-metals
1) Metals
Physical Properties
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- Exception:
conduct heat and electricity
have a luster
some are ductile
some are malleable
most are solids
Mercury is a liquid
- metal elements exhibit a positive electrical charge
2) Non-metals
Physical Properties
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not good conductors
usually brittle
not malleable
not ductile
some are solids, some liquids, some gases
- nonmetal elements exhibit a negative electrical
1 2 3 4 5 6 7 8
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B. Compounds
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substances composed of two or more elements combined chemically in definite proportions by mass
cannot be separated by physical means - only chemically
have both chemical and physical properties different from the constituent elements
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Examples of Compounds:
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salt
carbon dioxide
water
formaldehyde
NaCl
CO2
H2O
HCHO
C. Mixtures
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a combination of two or more substances not chemically united and NOT in definite proportion by mass
may be separated by physical means
elements or compounds may be present in any proportion
- embalming fluid is a mixture
- blood
- milk
- air
- saltwater
- HCHO gas dissolved in water and “mixed” with all the other constituents
Other examples of Mixtures
