Chem Definitions

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the closeness of a measurement to the true value of the quantity that is measured

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accuracy

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the amount of product actually obtained in a reaction

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actual yield

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an ion with a net negative charge

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anion

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the number of 12C atoms in exactly 12g of 12C; it equals 6.022 X 10^23

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Avogadro's number

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a substance capable of donating a proton (H+)

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bronsted acid

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a substance capable of accepting a proton

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bronsted base

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a solution that has the ability to resist small changes in pH upon the addition of small amounts of either acid or base

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buffer solution

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a substance that increases teh rate of a chemical reaction without itself being consumed

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catalyst

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an ion with a net positive charge

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cation

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processes in which one or more substances are converted into other substances.

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chemical reaction or chemical changes

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the area of chemistry concerned with the speeds, or rates, at which chemical reactions occur

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chemical kinetics

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a substance composed of atoms of two or more elements chemically united in fixed proportions

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compound

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a bond in which two electrons are shared by two atoms

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covalent bond

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the mass of a substance divided by its volume

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density

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the gradual mixing of one substance with another due to random molecular motion

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diffusion

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a procedure for preparing a less concentrated solution from a more concentrated solution

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dilution

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a substance that, when dissolved in water, results in a solution that can conduct electricity

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electrolyte

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the ability of an atom to attract electrons toward itself in a chemical bond

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electronegativity

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a substance that cannot be separated into simpler substances by chemical means

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element

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processes that absorb heat from the surroundings

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endothermic processes

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the capacity to do work or to produce change

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energy

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a biological catalyst

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enzyme

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a state in which there are no observable changes as time goes by

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equilibrium

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one or more reactants present in quantities greater than those needed to react with quantity of the limiting reagent

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excess reagents

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processes that give off heat to the surroundings

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exothermic processes

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energy can be converted from one form to another, but cannot be created or destroyed

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first law of thermodynamics

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a reaction equation which shows all soluble compounds in their ionic forms

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full ionic equation

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the transfer of thermal energy (energy associated with the random motion of atoms and molecules) between two bodies that are at a different temperature

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heat

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when reactants are converted to products, the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps

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Hess's law

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a special type of dipole-dipole interaction between molecules containing hydrogen bonded to an electronegative element. the most important examples involve nitrogen, oxygen and fluorine.

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hydrogen bond. for example, the attraction between a hydrogen on one water molecule and the oxygen atom on a second water molecule

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compounds other than organic compounds

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inorganic compounds

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a charged species

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ion

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a chemical compound composed of cations and anions combined so that the total positive and negative charges are equal

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ionic compound

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the electrostatic force that holds ions together in an ionic compound

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ionic bond

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the minimum energy required to remove an electron from an isolated atom or ion in its ground state

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ionization energy

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atoms having the saem number of protons but different numbers of neutrons

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isotopes

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unit of energy given by newton-meters

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joule

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energy available because of the motion of an object

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kinetic energy

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if an external stress is applied to a system at equilibrium, the system will adjust itself in such a way as to partially offset the stress

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le chatelier's principle

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the reactant used up first in a reaction

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limiting reagent

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properties that can be measured directly

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macroscopic properties

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elements that are good conductors of heat and electricity and have the tendency to form positive ions in ionic compounds

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metals

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a combination of two or more substances in which the substances retain their identitiy

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mixture

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the mass in g or kg of one mole of atoms, molecules, or other particles

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molar mass

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the number of moles of solute in one liter of solution

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molarity (M)

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a collection of Avogadro's number of objects

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mole. for example; a mole of h20 is 6.022 x 10^23 h20 molecules

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a compound consisting of atoms that are covalently bonded

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molecular compound

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a reaction equation which shows the complete chemical formulas of all reactants and products

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molecular equation

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a neutral aggregate of two or more atoms held together by covalent bonds

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molecule

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a reaction equation in which all spectator ions are removed leaving only the ions and molecules directly involved in the reaction

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net ionic equation

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a substance that, when dissolved in water, gives a soution that is not electrically conducting

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nonelectrolyte

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elements that are usually poor conductors of heat and electricity and have the tendency to gain electrons and form negative ions

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nonmetals

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a covalent bond in which the electrons are equally shared by two atoms, so there are no positive and negative ends

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nonpolar bond

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a molecule that doesn't posses a dipole moment

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nonpolar molecule

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an atom other than hydrogen tends to form bonds until it is surrounded by eight valence electrons

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octet rule

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the branch of chemistry that deals with carbon compounds

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organic chemistry

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the number of charges an atom would have in a molecule if electrons were transferred completely in the direction of the atoms with the higher electronegativity

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oxidation number

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the half-reaction that involves the loss of electrons

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oxidation reaction

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a substance that can accept electrons from another substance or increase the oxidation number in another substance

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oxidizing agent

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the ration of actual yield to theoretical yield, multiplied by 100%

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percent yield

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the negative logarithm of the hydrogen ion concentration

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pH

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a particle of light

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photon

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any property of a substance that can be observed without transforming the substance into some other substance

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physical property

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a covalent bond in which the bonding electrons are more strongly attracted by one of the bonding atoms creating partial positive and negative ends.

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polar bond. there is some degree of ionic hcaracter in this type of bond

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a molecule that possesses a dipole moment

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polar molecule

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energy available by virtue of an object's position

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potential energy

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any insoluble solid that separates from the solution

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precipitate

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the closeness of agreement of two or more measurements of the same quantitiy

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precision

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force applied per unit area

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pressure

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a reaction in which there is either a transfer of electrons or a change in the oxidation numbers of the substances taking part in the reaction

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redox reaction

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the half-reaction that involves the gain of electrons

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reduction reaction

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an ionic compound made up of a cation (other than H+) and an anion (other than OH- or O2-)

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salt

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at a given temperature, the solution that results when the maximum amount of a substance dissolves in a solvent

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saturated solution

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the number of meaningful digits in a measured or calculated quantity

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significant figures

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the maximum amount of solute that can be dissolved in a given quantitiy of solvent at a specific temperature

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solubility

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the substance present in smaller amount in a solution

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solute

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a homogeneous mixture of two or more substances

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solution

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the substance present in larger amount in a solution

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solvent

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the amount of heat energy required to raise the temperature of one gram of the substance by one degree Celsuis

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specific heat

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ions that are not involved in the overall reaction

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spectator ions

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the amount of product predicted by the balanced quation when all of the limiting reagent has reacted

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theoretical yield

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the study of heat changes in chemical reactions

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thermochemistry

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the scientific study f the interconversion of heat and other forms of energy

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thermodynamics

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the gradual addition of a solution of accurately known concentration to another solution of unknown concentration until the chemical reaction between the two solutions is complete

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titration

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a reaction equation in whcih all spectator ons are removed leaving only the ions and molecules directly involved in the reaction

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net ionic equation