Download compound - Coal City Unit #1

How is Matter Classified?
• Matter is classified using chemical and
physical props.
Pure Substances
• a sample of matter that has definite chemical
and physical properties
• Elements
• Compounds
ATOM
• the basic unit of matter
• all matter is composed of atoms
ELEMENTS
• simplest substances from which more
complex substs. are made
• ea. elem. contains single type of atom
• 111 diff. elements discovered to date
• represented by symbols – usually one or two
letters
1st letter is always capitalized,
second letter is always sm. case
• most symbols come from their names
• some symbols come from Latin or Greek names
• some elem. named in honor of person or place they
were discovered
• ea. elem. has its own unique set of chem. and
physical props.
Small number of elements make
up most common substs.
• H is most common element
• Living things are made primarily of C, H, O,
and N
MOLECULE
• neutral group of atoms held together by
covalent bonds
• two or more atoms combined in a definite ratio
• atoms may be of the same or different elements
Elements may exist as single
atoms or as molecules
• Helium gas consists of single atoms
(monatomic gas)
• Nitrogen gas consists of molecules
• Ea. molec. consists of two nitrogen atoms (diatomic
gas)
7 diatomic gases are elements:
• Bromine
• Iodine
• Nitrogen
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Chlorine
Hydrogen
Oxygen
Fluorine
ALLOTROPES
• one of a number of different molecular or
crystalline forms of an element
• diff. forms of the same element
• Oxygen consists of 2 allotropes – O2 and O3
(ozone)
• Carbon has many allotropes
• most common are graphite and diamond
• Allotropes have different properties
COMPOUND
• the product that results when two or more
different elements are chemically combined
Two types of compounds:
• Ionic compounds – consist of positively and
negatively charged ions
• ION – an atom or group of atoms w/ an electrical
charge
• Covalent compounds – made of neutral
molecules
ACID
• a class of compounds whose water solns. taste
sour, turn blue litmus paper red, and react
with bases to form salts (ionic compounds)
pH
• a numerical scale used to express acidity
• 0 to 14
• 7 is neutral
• comps. w/ pH less than 7 are acids
• comps. w/ pH greater than 7 are bases
BASE
• a class of compounds that taste bitter, feel
slippery in water soln., turn red litmus to blue,
and react with acids to form salts
ORGANIC COMPOUNDS
• covalent compounds containing carbon
(except carbonates and oxides)
INORGANIC COMPOUNDS
• compounds outside the organic family of
compounds
Compounds are represented by
formulas
• molecular formula - C12H22O11 (sugar)
• ionic formula – NaCl (table salt)
• shows numbers of atoms of ea. elem. present in
compound
Structural Formulas
• show the exact number of atoms present in a
molecule and how these atoms are bonded to
one another
• lines represent the bonds betw. atoms
MIXTURE
• a collection of 2 or more pure substs.
physically mixed together
• proportions can vary
• properties can vary
ALLOY
• solid mixture (usually mixture of metals)
Two diff. classifications of
mixtures:
HOMOGENEOUS MIXTURE
• a mixture containing substs. that are uniformly
distributed
• solution
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salt water
koolaid
tea
brass (alloy)
• all regions are identical in composition & properties
HETEROGENEOUS MIXTURE
• a mixture containing substs. that are not
uniformly distributed
• some regions have different properties than other
regions
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dirt
granite
choc. chip ice cream
veg. soup
ice water
How mixtures differ from
compounds:
• Props. of mixtures reflect props. of
components. Props. of compounds do not
• reflect. props. of elems. that compose it.
• Comps. have definite composition. Composition of
mixtures can vary.
Most mixtures can be separated by
physical means. Some mixtures
may need to be separated by
chemical means.
• react one component so it can be removed easier
All compounds must be separated
by chemical means