Ch 8 section 2 Flashcards
it is useful to classify reactions according to
various similarities and regularities
there are several ways to classify chemical reactions, and none are entirely
satisfactory
in a synthesis reaction (composition reaction) two or more substances combine to
form a new compound
synthesis reaction: A + X→
AX
A and X can be
elements or compounds, AX is a compound
almost all metals react with oxygen to form
oxides
the group 1 and group 2 elements react similarly with sulfur, forming
sulfides with formulas M2S and MS
some metals combine with oxygen to produce
two different oxides
the particular oxide formed depends on the conditions surrounding the
reactants
nonmetals also undergo synthesis reactions with oxygen to form
oxides
most metals react with halogens to form either
ionic or covalent ompounds
the halogens undergo synthesis reactions with many different
metals
fluorine in particular is so reactive that it combines with almost
all metals
sodium fluoride is added to water supplies in trace amounts to
provide fluoride ions which help prevent tooth decay in people who drink the water
active metals are highly
reactive metals
oxides of active metals react with
water to produce metal hydroxides
many oxides of nonmetals in the upper right portion of the periodic table react with water to produce
oxyacids
sulfurous acid further reacts with oxygen to form sulfuric acid, one of the main ingredients in
acid rain
certain metal oxides and nonmetal oxides react with oeach other in synthesis reacts to
form salts
in a decomposition reaction, a single compound undergoes a reaction that produces
two or more simpler substances
decomposition reactions are the oppposite of
synthesisreactions
decomposition reaction AX→
A+X
Most decomposition reactions take place only when energy in the form of
electricity or heat is added
the simplest kind of decomposition reaction is the decomposition of a
binary compound into its elements
the decomposition of a substance by an electric current is called
electrolysis
oxides of the less active metals decompose into their
elements when heated
when a metal carbonate is heated, it breaks down to produce a
metal oxide and carbon dioxide gas
all metal hydroxides except those containing group 1 metals decompose when heated to yield
metal oxides and water
when a metal chlorate is heated, it decomposes to produce a
metal chloride and oxygen
certain acids decompose into
nonetals and water
in a single-displacement reaction (replacement reaction) one element replaces a
similar element in a compound
many single displacement reactions take place in
aqueous solution
the amount of energy involved in this typ eof reaction is usually smaller than the amount involved in
synthesis or decomposition reactions
single displacement reactions
A+BX→
Y+BX→
AX+B
BY+X
the most active metals react vigorously with water to produce
metal hydroxides and hydrogen
less active metals react with steam to from a
metal oxide and hydrogen gas
the more active metals react with certain acidic solutions, replacing the
hydrogen in the acid
the reaction products (displacement of hydrogen in acid by metal) are a metal
compound (salt) and hydrogen gas
in another type of single-displacement reaction one halogen replaces
another halogen in a compound
fluorine can replace any of the other halogens in their
compounds
each halogen is less active than the one above it in the p
periodic table
in double displacement reactions the ions of two compound exchange
places in an aqueous solution to form two new compounds
one of the compounds formed is usually a precipitate, or a
molecular compound
double displacement reaction
AX+BY→
AY+BX
the formation of a precipitate occurs when the cations of one reactant combine with the
anions of another reactant to form an insoluble or slightly soluble compound
in some double displacement reations one of the products is an insoluble gas that
bubbles out of the mixture
in some double dis. reactions a very stable molecular compound is
one of the products
in a combustion reaction, a substance combines with oxygen, releasing a
large amount of energy in the form of light and heat
