Glossary of Chem 1H semes. 2 cards

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formula for: avg. rate of a reaction (reaction rate)
avg. rate= ^(quantity)/^t
Collision Theory
States that atoms, ions, and molecules must collide in order to react. (They must collide w/ correct orientation/they must have sufficient energy when colliding to form the activated complex)
activated complex
a temporary, unstable arrangement of atoms that may form products or may break apart to re-form reactants. (AKA transition state)
activation energy
the minimum amount of energy that reacting particles must have ot form the activated complex.

-it influences reacion rate (high Ea=few collisions will have enough energy to produce activated complex>reaction rate is low/ low Ea=more collisions will have enough energy to react, reaction rate will be higher)
how is reaction rate affected with concentration?
concentration increase=increased rate

concentration decreases=decreased rate
how does surface area affect reaction rates?
greater surface area=faster reaction

less surface area=slower reaction
how does temp. affect reaction rate?
increase temp. increases rate
an enzyme , or a substance that increases teh rate of a chemical reaction without itself being consumed in teh reaction.

-not included in chem. equation
a substance that is the opposite of a catalyst

-slows down reaction rates/some prevent teh reaction from happening at all.
heterogenoeous catalyst/homogenous catalyst
it exists in a physical state different than that of the reaction it catalyzes
-homogenous catalyst: exists in teh physical state that is the same as teh reaction it catalyzes (ex: aqeous solution and aqeous solution)
rate law for a one step reaction
general rate law for more-than-one step reaction
method of intial rates
determines reaction order by comparing the initial rates of a reaction carried out w/ varying reactant concentrations
instantaneous rate
rate of decomposition at a specific time

(find the general rate law and multiply it out)
complex reaction
one that consists of 2 or more elementary steps
reaction mechanism
the complete sequence of elementary steps that make up a complex reaction
a substance produced in one elementary step and consumed in a subsequent elementary step.

-do not appear in net chemical equation
rate-determining step
the slowest of the elementary steps in a complex reaciton.
acidic solution
-contains more H+ ions than OH- ions
basic solution
contained more OH- ions than H+ ions.
neutral solution
contains equal amount of H+ and OH- ions
Arrhenius model
an acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution
-base is a substance that contains a hydroxide group and dissociates to produce a hydroxide ion in aqueous solution.

es: HCL > H+ + Cl-
ex: NaOH > Na+ + OH=
Bronsted-Lowry model
an acid is a hydrogen-ion donor and a base is a hydrogen-ion accetor.
conjugate acid
the species produced when a base accepts a hydrogen ion from teh acid.
conugate base
species that results when an acid donates a hydrogen ion to a base.
conugate acid-base pair
consists of two substances related to eachother by the donating and accepting of a single hydrogen atom
the term used to name substances such as water that can be both an acid and a base
strong acid/weak acid
acids that ionize completely/an acid that ionizes only partially in dilute aqueous solution

-weak acids produce fewer ions and thus cannot conduct electricity as efficiently as strong acids.
if an acid is strong..its conjugate base is ____
acid ionization constant
the value of the equilibrium constant expression for the ionization of a weak acid.
strong base
dissociates entirely into metal ions an dhydroxide ions

(metallic hydroxides are strong bases)
weak base
ionizes only partially in dilute aqueous solution to form teh conjugate acid of the base and hydroxide ion.
neutralization reaction
a reaction in which an acid and a base react in aqueous solution to produce a salt and water
-made up from cation from a base and a anion from an acid
-doubt-replacement reaction
a method for determining the concentration of a solution by reacting a known volume of the solution with a solution of known concentration.
equivalence point
the stoichiometric point when teh OH equals the H
salt hydrolysis
the anions of the dissociated salt accept hydrogen ions from water or teh cations of the dissociated salt donate hydrogen ions to water
redox reactions
a reaction in which electrons are transferred from one atom to another
the loss of electrons from atoms of a substance
-oxidation number goes up
the gain of electrons by atoms of a substance
-oxidation number is reduced
oxidizing agent
substance that oxidizes another substance by accepting its electrons (the substance that is reduced)
reducing agent
the substance that reduces antoher substance by losing electrons (the substance that is oxidized)
oxidation-number method
the total increase in oxidation numbers(oxidation) must equal the total decrease of oxidation numbers (reduction) of the atoms involved in the reation. this is the technique you use to balance it
half reaction
one of teh two parts of a redox reaction-oxidation half alone or reduction half alone
covalent bond
the chemical bond that results from teh sharing of valence electrons
formed when two or more atoms bond covalently
Lewis Structures
use electron-dot diagrams to show how electrons are arranged in molecules
ex: Hydrogen is represented by H:H or H-H
sigma bonds
single covalent bonds
-occurs when electronspair is shared in an area centered between two atoms.
-when two atoms share electrons, valence atomic orbital of one atom overlaps or merges w/ the valence atomic orbital of another atom
pi bon
formed when parallel orbitals overlap to share electrons
any acid that contains hydrogen and an oxyanion
structural formula
uses letter symbols and bonds to show relative positions of atoms
condition that occurs when more than one valid Lewis Structure can be written fora molecule or ion.
coordinate covalent bond
when an atom donates a pair of electrons to be shared with an atom or ion that needs two electrons to become stable
VSEPR model
model based on an arrangem,ent that minimizes the repulsion of shared and unshared pairs of electrons around the central atom.
process in which atomic orbitals are mixed to form new, identical hybrid orbitals.
polar covalent bond
when there is unequal sharing of electrons
-large differences in electronegativeity

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