How can we help?

You can also find more resources in our Help Center.

95 terms

Ch. 2: Atoms, Molecules, and Ions

STUDY
PLAY
atomic theory
explanation of the structure of matter in terms of different combinations of very small particles
atom
minute particle of which matter is composed; the smallest part of an element that can enter into chemical reaction
compound
type of matter composed of atoms of two or more elements chemically combined in fixed proportions
chemical reaction
rearrangement of atoms present in reacting substances to give new chemical combinations present in the substances formed
law of multiple proportions
when two elements form more than one compound, the masses of one element in these compounds for a fixed mass of the other element are in ratios of small whole numbers
atomic symbol
one- or two-letter notation used to represent an atom corresponding to a particular element
nucleus
positively charged central core of an atom; contains most of the atom's mass
electron
very light, negatively charge particle that exists in the region around the positively charged nucleus
cathode
negative electrode
anode
positive electrode
cathode rays
rays that originate from the cathode, or negative electrode, in a gas-discharge tube
coulomb (C)
unit of electric charge
nuclear model
most of the mass of an atom is concentrated in a positively charged center, called the nucleus, around which negatively charge electrons move
proton
nuclear particle having a positive charge equal to +e (e being the charge on an electron) and a mass more than 1800 times that of an electrons
atomic number (Z)
number of protons in an atomic nucleus; identifies the element
element
substance whose atoms all have the same atomic number
neutron
neutral particle of mass almost identical to that of a proton, but without electric charge
mass number (A)
total number of protons and neutrons in a nucleus
nuclide
an atom characterized by a definite atomic number and mass number
nuclide symbol
symbol for a nuclide in which the mass number is written as a superscript and the atomic number as a subscript on the left of the symbol for the element
isotopes
atoms whose nuclei have the same atomic number but different mass number
mass spectrometer
instrument used to determine atomic mass
atomic mass unit (amu)
mass unit equal to exactly one-twelfth the mass of a carbon-12 atom
atomic weight
average atomic mass for the naturally occurring element, expressed in atomic mass units
mass spectrum
chart recording from the mass spectrometer that shows the relative number of atoms for various masses
fractional abundance
fraction of the total number of atoms that is composed of a particular isotope
periodic table
tabular arrangement of elements in rows and columns, highlighting the regular repetition of properties of the elements
period (of periodic table)
elements in any one horizontal row of the periodic table
group (or periodic table)
elements in any one column of the periodic table
main-group (representative) elements
elements in the A groups of the periodic table
transition elements
elements in the B groups of the periodic table
inner-transition elements
two rows of elements at the bottom of the periodic table
lathanides
first of the two rows of inner-transition elements
actinides
second of the rows of inner-transition elements
alkali metals
elements in Group IA of the periodic table
halogens
elements in Group VIIA of the periodic table
metal
substance or mixture that has a characteristic luster or shine and is generally a good conductor of heat and electricity; elemental metals are to the left of the staircase line on the periodic table
malleable
able to be hammered into sheets
ductile
able to be drawn into wire
nonmetal
element to the right of the staircase line on the periodic table; exhibits characteristics different from those of metals
metalloid (semimetal)
element bordering the staircase line on the periodic table; exhibits both metallic and nonmetallic properties
semiconductors
elements that, when pure, are poor conductors of electricity at room temperature but become good conductors at higher temperatures
doping
adding small amounts of other element to pure semiconductor elements to make them very good electrical conductors
chemical formula
notation that uses atomic symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in the substance
molecule
definite group of atoms that are chemically bonded together and, as a group, electrically neutral
molecular substance
substance composed of molecules of all which are alike
molecular formula
gives the exact number of different atoms of an element in a molecule
structural formula
chemical formula that shows which atoms are bonded to one another in a molecule
polymers
very large molecules that are made up of a number of smaller molecules repeatedly linked together
monomers
the small molecules that are linked together to form a polymer
ion
electrically charged particle obtained from an atom or chemically bonded group of atoms by addition or removal of one or more electrons
anion
negatively charged ion
cation
positively charged ion
ionic compound
compound composed of cations and anions
crystal
solid having a regular three-dimensional arrangement of either ions, atoms, or molecules
formula unit
group of atoms or ions explicitly symbolized in the chemical formula
organic compounds
molecular substance that contain carbon
hydrocarbons
compounds containing only hydrogen and carbon
functional groups
reactive portion of a molecule that undergoes predictable reaction
alcohol
molecule that contains an —OH functional group
ether
organic molecule that contains an oxygen atom between two carbon atoms
chemical nomenclature
systematic naming of chemical compounds
organic compounds
molecular substances that contain carbon combined with other elements, such as hydrogen, oxygen, and nitrogen
inorganic compounds
compounds composed of elements other than carbon
monatomic ion
ion formed from a single atom
Stock system
system for naming compounds in which a Roman numeral within parentheses follows the first-named element ot indicate its charge or oxidation number
oxidation stare or oxidation number
hypothetical charge assigned in accordance with certain rules; denoted with a Roman numeral following the name of the metal atom
-ous
in an older system of nomenclature, a suffix added to the stem name of an element to indicate the cation of lower charge; also indicates the oxoacid with fewer oxygen atoms
-ic
in an older system of nomenclature, a suffix added to the stem name of an element to indicate the cation of higher charge; indicates the oxoacid with more oxygen atoms; also indicates an acid solution obtained from binary compounds of hydrogen and nonmetals
-ide
suffix added to the stem name of the element to name monatomic anions or the more electronegative element in binary compounds
polyatomic ion
ion consisting of two or more atoms chemically bonded together and carrying a net electric charge
oxoanion (oxyanion)
anion composed of oxygen with another element, which is the central element
acid
molecular compound that can yield one or more hydronium ions, H3O+, an an anion for each acid molecule when the acid dissolves in water
oxoacid
acid containing hydrogen, oxygen, and another element
-ate
suffix denoting the oxoanion with the greater number of oxygen atoms
-ite
suffix denoting the oxoanion with the lesser number of oxygen atoms
hypo-
prefix denoting the oxoacid or oxoanion with the least number of oxygen atoms in the series
per-
prefix denoting the oxoacid or oxoanion with the greatest number of oxygen atoms in the series
acid anions
anions that have hydrogen atoms they can lose as hydronium ions, H3O+
di-
Greek prefix meaning two
thio-
prefix meaning an oxygen in the root ion name has been replaced by a sulfur atom
binary compound
compound composed of only two elements
hydro-
prefix added to the stem name of the nonmetal to name the acid solution obtained from binary compound of hydrogen and nonmetals
hydrate
compound that contains water molecules weakly bound in its crystals
chemical equation
symbolic representation of a chemical reaction in terms of chemical formulas
reactant
starting substance in a chemical reaction; appears to the left of the arrow in a chemical reaction
product
substance that results form a chemical reaction; appears to the right of the arrow in a chemical equation
coefficient
number that appears in front of a formula in a chemical equation and gives the relative number of molecules or formula units of a substance involved in the reaction
(g)
phase label placed after a formula in a chemical equation to indicate that the substance is a gas
(l)
phase label placed after a formula in a chemical equation to indicate that the substance is a liquid
(s)
phase label placed after a formula in a chemical equation to indicate that the substance is a solid
(aq)
phase label placed after a formula in a chemical equation to indicate that the substance is in aqueous (water) solution
catalyst
substance that speeds up a reaction without undergoing any net change itself
balanced
describes a chemical equation having correct coefficients
balancing by inspection
trial-and-error method of balancing a chemical equation by writing appropriate coefficient until there is the same number of any one elemental atom on each side of the arrow