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26 Cards in this Set
- Front
- Back
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chemical reaction
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the process by which the atoms of one or more substances are rearranged to form different substances
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evidence of chemical reactions
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- temp. change (unexpected)
- release of energy (in the form of heat and light) - absorbtion of heat - color change - odor - gas bubbles - formation of a solid |
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chemical equation
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(balanced)
a statement that uses chemical formulas to show the identities and relative amounts of the substances involved in a chemical reaction - shows how the law of conservation of mass is obeyed (or that the number of atoms of each reactant and each product is equal on both sides of the arrow) |
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coefficient
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describes the lowest whole-number ratio of the amounts of all of the reactants and products
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what are the 5 types of chemical reactions?
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synthesis
combustion decomposition single-replacement double-replacement |
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synthesis reaction
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a chemical reaction in which 2 or more substances react to produce a single product
- when 2 ELEMENTS react, the reaction is ALWAYS a synthesis A + B -- AB - A and B can be elements or compounds, but AB will ALWAYS be a compound |
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combustion reaction
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oxygen combines with a substance and releases energy in the form or heat or light
M(s) + 02(g) -- MOx(s) - M is a metal N(s) + 02(g) -- NOy(?) - N is a nonmetal CxHy(Oz) + 02(g) -- CO2(g)+ H20(g) - (0z) = sometimes oxygen |
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decomposition reaction
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a single compound breaks down into 2 or more new elements or new compounds
AB -- A + B - AB is ALWAYS a compound - A and B can be elements or compounds - often require an energy source to occur (heat, light etc.) - involves the transfer of electrons from one atom to another |
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single-replacement reaction
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the atoms of one element replace the atoms of another element in a compound
- use the activity series M(s) + NX(aq) -- N(s) + MX(aq) metal + compound(aq)-- replaced metal(s)or H2(g) + new compound(aq) nonmetal + compound(aq)--replaced nonmetal + new compound(aq) *M must be higher than N on the activity series for a reaction to occur - involves the transfer of electrons from one atom to another |
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activity series
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use in determining products of single-replacement reactions
- a specific metal can replace any metal listed BELOW it that is in a compound - no reaction occurs when the metal is listed above it - most active are on the top and least active on the bottom |
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double-replacement reaction
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a replacement reaction which involves an exchange of ions between 2 compounds
MX(aq) + NY(aq)--MY + NX - either MY or NX must be a precipitate (insoluble), gas, or water - the positive and negative ions of 2 compounds switch places |
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precipitate
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a solid produced during a chemical reaction in a solution
- ALL double-replacement reactions produce either a precipitate, a gas, or water |
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oxidation-reduction reaction
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also called a redox reaction
a reaction in which electrons are transferred from one atom of another atom |
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oxidation
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the loss of electrons from atoms of a substance
there must be an accompanying process (reduction) the electrons lost by the oxidized substance must be accepted by another substance Ex: Na-- Na+ + e- |
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reduction
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the gain of electrons by atoms of a substance
Ex: Cl2 + 2e- -- 2Cl- |
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LEO GER
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Loss of Electrons is Oxidation
Gain of Electrons is Reduction |
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oxidation number
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(of an atom in an ionic compound)
the number of electrons lost or gained by the atom when it forms ions oxidation number: +3, -3 ionic charge: 3+, 3- increases when an atom is oxidized decreases when an atom is reduced |
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oxidizing agent
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the substance that oxidizes another substance by accepting its electrons
the substance that is being reduced |
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reducing agent
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the substance that reduces another substance by losing electrons
supplies electrons to the substance getting reduced (gaining electrons) it is oxidized b/c it loses electrons |
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oxidation number of an uncombined atom
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= 0
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oxidation number of a monatomic ion
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= the change on the ion
Ex: Br- oxidation number = -1 |
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oxidation number of the more electronegative atom in a molecule or a complex ion
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= the change that is the same as it would have if it were an ion
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oxidation numbers of fluorine, oxygen, and hydrogen
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In compounds:
F = -1 (same as ionic charge) O = -2 (same as ionic charge) EXCEPTION: +2 when bonded to F; -1 in peroxides H = +1 (same as ionic charge) EXCEPTION: -1 when bonded to less electronegative metals to form hydrides |
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oxidation numbers of metals of groups 1A and 2A and Al
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form compounds in which the metal atom always has a positive oxidation number equal to its number of valence electrons
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sum of oxidation numbers in a neutral compound
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= 0
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sum of the oxidation numbers in a polyatomic ion
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= the charge of the ion
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