Copy of `Cliffs Notes - Science terms`

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Cliffs Notes - Science terms Category: Sciences > Chemistry Date & country: 04/01/2014, USA Words: 147

acid ionization constant
the equilibrium constant describing the degree of ionization of an acid.

actinides
the row of elements below the periodic table, from thorium to lawrencium.

alkyne
a hydrocarbon with one or more triple bonds.

alpha particle
a cluster of 2 protons and 2 neutrons emitted from a nucleus in one type of radioactivity.

alkaline earths
the column of elements from beryllium to radium.

alkane
a hydrocarbon without a double bond, triple bond, or ring structure.

alkene
a hydrocarbon with one or more double bonds and no triple bond.

alkali
synonym for base.

alkali metals
the column of elements from lithium to francium.

anion
a chemical species with a negative charge.

anode
the negative electrode at which oxidation occurs.

aqueous
refers to a solution with water as solvent.

aromatic
refers to an organic compound with a benzene-like ring.

atomic weight
the weight in grams of one mole of the chemical element; approximately the number of protons and neutrons in the nucleus.

atom
the smallest amount of an element; a nucleus surrounded by electrons.

atomic number
the number of protons in the nucleus of the chemical element.

Avogadro's number
6.02 x 10²³, the number of molecules in 1 mole of a substance.

Avogadro's law
equal volumes of gases at the same temperature and pressure that contain the same number of molecules.

base
a compound that yields OH^- ions in solution or a solution in which the concentration of OH^- exceeds H⁺.

beta particle
an electron emitted from a nucleus in one type of radioactivity.

Boyle's law
the volume of a gas varies inversely with pressure.

boiling point
the temperature at which a liquid changes to a gas.

boiling point elevation
an increase in the boiling point of a solution, proportional to the concentration of solute particles.

cathode
the electrode at which reduction occurs.

cation
an atom or molecule with a positive charge.

catalyst
a substance that accelerates a chemical reaction without itself being consumed.

calorie
a unit of energy, equal to 4.184 joules.

chemical formula
a representation of a compound to show its composition using symbols and subscript numbers.

Charles' law
the volume of a gas varies directly with absolute temperature.

chemical equation
a shorthand way of describing a chemical change using symbols of elements and formulas of compounds.

covalent bond
atoms linked together by sharing valence electrons.

conjugate
an acid and base that are related by removing or adding a single hydrogen ion.

congeners
elements with similar properties, arranged in columns of the periodic table.

concentration
the relative abundance of a solute in a solution.

compound
a substance formed by the chemical combination of two or more elements.

critical point
a point in a phase diagram where the liquid and gas states cease to be distinct.

crystalline
the regular, geometric arrangement of atoms in a solid.

decomposition
a chemical reaction in which a compound is broken down into simpler compounds or elements.

dissociation
the separation of a solute into constituent ions.

element
a substance that cannot be decomposed; each chemical element is characterized by the number of protons in the nucleus.

electronegativity
a number describing the attraction of an element for electrons in a chemical bond.

electromotive
force the electrical potential produced by a chemical reaction voltage.

electron
a light subatomic particle with negative charge; found in orbitals surrounding an atomic nucleus.

electrolysis
the decomposition of a substance by an electric current.

electrolyte
a substance that forms ions when dissolved in water.

electrode
the point in an electrochemical cell at which reduction or oxidation occurs.

electrochemical
cell a device that uses a chemical reaction to produce an electric current.

EMF
See electromotive force.

entropy
the thermodynamic quantity measuring the disorder of a substance.

energy
the concept of motion or heat required to do work.

enthalpy
the thermodynamic quantity measuring the heat of a substance.

endothermic
refers to a reaction that requires heat.

equilibrium
constant the ratio of concentrations of products to reactants for a reaction at chemical equilibrium.

equilibrium
a balanced condition resulting from two opposing reactions.

exothermic
refers to a reaction that releases heat.

faraday
a unit of electric charge equal to that on 1 mole of electrons.

Faraday's laws
two laws of electrolysis relating the amount of substance to the quantity of electric charge.

fluid
a liquid or gas.

freezing point depression
the decrease in freezing point of a solution, proportional to the concentration of solute particles.

free energy
the thermodynamic quantity measuring the tendency of a reaction to proceed; also called Gibbs free energy.

freezing point
the temperature at which a liquid changes to a solid.

fusion
melting.

gas constant
R equals 0.082 liter-atmospheres per mole-degree.

gas
a state of matter in which molecules are widely separated, fluid, expandable, and compressible.

ground state
the electronic configuration of lowest energy for an atom.

group
a column of elements in the periodic table.

gram formula
weight an amount of a substance equal in grams to the sum of the atomic weights.

half-reaction
an oxidation or reduction reaction with free electrons as a product or reactant.

halogens
the column of elements from fluorine to astatine.

heat
a form of energy that spontaneously flows from a warm body to a cold body.

heat capacity
the amount of energy needed to raise the temperature of a substance by one degree Celsius.

hydroxide
refers to the OH- ion.

hydrocarbon
an organic compound containing only carbon and hydrogen.

hydrogen bond
a weak, secondary bond between a partially positive hydrogen atom and a partially negative N, O, or F atom. An inter-molecular force of attraction.

ideal gas equation
the equation relating the volume of a gas to its pressure, temperature and moles of gas.

inert gases
the column of elements from helium to radon; also called noble gases.

ionic bond
atoms linked together by the attraction of unlike charges.

ion
an atom with an electric charge due to gain or loss of electrons.

ionization
adding or subtracting electrons from an atom; alternatively, the dissociation of a solute into ions.

isotope
a variety of an element characterized by a specific number of neutrons in the nucleus.

isomers
several molecules with the same composition but different structures.

isoelectronic
refers to several dissimilar atoms or ions with identical electronic configurations.

joule
a unit of energy equal to 0.239 calorie.

lanthanides
the row of elements beneath the periodic table, from cerium to lutetium; also called rare earths.

Le Chatelier's principle
a system that in equilibrium is disturbed adjusts so as to minimize the disturbance.

litmus
an indicator that turns red in acid and blue in alkaline solution.

liquid
a state of matter in which the molecules are touching, fluid, incompressible.

metallic bond
atoms linked together by the migration of electrons from atom to atom.

metals
the elements in the middle and left parts of the periodic table, except for hydrogen.

melting point
the temperature at which a solid changes to a liquid.

molecule
a group of atoms linked together by covalent bonds.

molecular formula
describes the ratio of elements in a molecule.

mole
an amount of a substance equal in grams to the sum of the atomic weights.

mole fraction
the fraction of moles (or molecules) of one substance in the total moles (or molecules) of all substances in the mixture. If the mole fraction of substance A is 0.1, one-tenth of all the molecules in a mixture are A molecules.

molarity
the number of moles of solute in 1 liter of solution.

molar heat capacity
the amount of heat required to raise the temperature of 1 mole of substance 1 degree Celsius.

molality
the number of moles of solute in 1 kilogram of solvent.

neutron
a heavy subatomic particle with zero charge; found in an atomic nucleus.

neutralization
the chemical reaction of an acid and base to yield a salt and water.

noble gases
the column of elements from helium to radon; also called inert gases.