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any substance that has a definite composition


the science of matter


the smallest unit of an element that maintains the properties of that element

change of state

a physical change of a substance from one state to another

chemical change

a change in which one or more substances are converted into different substances

chemical property

the ability of a substance to undergo a change that transforms it into a different substance

chemical reaction

the process by which one or more substances change to produce one or more different substances


a substance made up of atoms of two or more different elements joined by chemical bonds


a pure substance made of only one kind of atom

extensive property

a property that depends on the amount of matter present


a state of matter that has no definite shape or volume


not uniform throughout


uniform in composition

intensive property

a property that does not depend on the amount of matter present


a substance in the fluid state of matter having no fixed shape but a fixed volume


a measure of the amount of matter in an object


anything that has mass and takes up space


a blend of two or more kinds of matter, each of which retains its own identity and properties

physical change

a change in a substance that does not involve a change in the identity of the substance

physical property

a characteristic that can be observed or measured without changing the identity of the substance


high temperature physical state of matter in which atoms lose their electrons

pure substance

a substance that has a fixed composition and differs from a mixture in that every sample of a given pure substance has exactly the same characteristic properties and composition


the substances that react in a chemical change


the state in which matter has a definite shape and volume


A homogeneous mixture of two or more substances


Elements in the same vertical column of the periodic table; also called a group


Vertical column of elements in the periodic table


an element that is a good conductor of heat and electricity


an element that has some characteristics of metals and some characteristics of nonmetals


an element that is a poor conductor of heat and electricity


a horizontal row of elements in the periodic table


testable statement


An explanation or representation of something that cannot be seen

scientific method

a logical procedure for gathering information about the natural world, in which experimentation and observation are used to test hypotheses.


a specific portion of matter in a given region of space that has been selected for study during an experiment or observation


a broad generalization that explains a body of facts or phenomena

conversion factor

a ratio derived from the equality between two different units that can be used to convert from one unit to the other.


the ratio of the mass of a substance to the volume of the substance

derived unit

Unit of measurement obtained by combining SI units (density= mass/volume)


something that has magnitude, size, or amount


Le Système International d'Unités, or the International System of Units, which is the measurement system that is accepted worldwide


the amount of space occupied by an object


The measure of the force of gravity on an object


the closeness of measurements to the correct or accepted value of the quantity measured

directly proportional

two quantities that give a constant value when one is divided by the other.

indirectly proportional


percent error

a value calculated by subtracting the experimental value from the accepted value, dividing the difference by the accepted value, and then multiplying by 100


closeness of a set of measurements of the same quantity made in the same way

scientific notation

numbers are written in the form M x 10^n, where the factor M is a number greater than or equal to 1 but less than 10 and n is a whole number

significant figures

any digit in a measurement that is known with certainty plus one final digit,which is somewhat uncertain or is estimated.

law of conservation of mass

Mass is neither destroyed nor created during ordinary chemical reactions or physical changes

law of definite proportions

a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound

law of multiple proportions

if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers


the smallest unit of an element that maintains the properties of that element

nuclear forces

short-range proton-neutron, proton-proton, and neutron-neutron forces hold the nuclear particles together

atomic mass

number of protons

atomic numbers

the number of protons in the nucleus of an atom

average atomic mass

the weighted average of the atomic masses of the naturally occurring isotopes of an element

avogadro's number



atoms of the same element that have different masses

mass number

the total number of protons and neutrons in an atom

molar mass

the mass of one mole of a pure substance


the amount of a substance that contains as many particles as there are atoms in exactly 12g of carbon-12


The general term for any isotope of any element; another term for an atom that is identified by the number of protons and neutrons in its nucleus

continuous spectrum

the emission of a continuous range of frequencies of electromagnetic radiation

electromagnetic radiation

a form of energy that exhibits wavelike behavior as it travels through space

electromagnetic spectrum

All of the frequencies or wavelengths of electromagnetic radiation

excited state

a state in which an atom has a higher potential energy than it has in its ground state


the number of waves that pass a given point in a specific time, usually one second

ground state

the lowest energy state of an atom

line-emission spectrum

series of specific wavelengths of emitted light created when the visible portion of light from excited atoms in shined through a prism

photoelectric effect

The emission of electrons from a metal when light shines on the metal


a particle of electromagnetic radiation having zero mass and carrying a quantum of energy


the minimum quantity of energy that can be lost or gained by an atom


The distance between corresponding points on adjacent waves

angular momentum quantum number

the quantum number that indicates the shape of the orbital

Heisenberg uncertainty principle

it is impossible to determine simultaneously both the position and velocity of an electron or any other particle

magnetic quantum number

the quantum number that indicates the orientation of an orbital around the nucleus

hund's rule

orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin

inner shell electrons

an electron that is not in the highest occupied energy level

noble gases

helium, neon, argon, krypton, xenon, and radon

noble gas configuration

An outer main energy level fully occupied, in most cases, by eight electrons

pauli exclusion principle

no two electrons or protons or neutrons in a given system can be in states characterized by the same set of quantum numbers


a three dimensional region around the nucleus that indicates the probable location of an electron

quantum numbers

numbers that specify the properties of atomic orbitals and of their electrons

quantum theory

a mathematical description of the wave properties of electrons and other very small particles

spin quantum number

The quantum number that has only two possible values, +1/2 and -1/2, which indicate the two fundamental spin states of an electron in an orbital

aubau principle

an electron occupies the lowest-energy level that can receive it

electron configuration

arrangement of electrons in an atom

highest occupied energy level

the electron-containing main energy level with the highest principal quantum number


one of the 14 elements with atomic numbers from 90 (thorium, Th) through 103 (lawrencium, Lr)


one of the 14 elements with atomic numbers from 58 (cerium, Ce) to 71 (lutetium, Lu)

periodic law

the physical and chemical properties of the elements are periodic functions of their atomic numbers

periodic table

an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group

alkali metals

the elements of Group 1 of the periodic table (lithium, sodium, potassium, rubidium, cesium, and francium)

alkaline earth metals

The Group 2 elements (Be, Mg, Ca, Sr, Ba, Ra)


the elements of Group 17 (fluorine, chlorine, bromine, iodine, and astatine)

main group elements

Those elements occupying the s and p blocks of the periodic table.

transition elements

one of the d-block elements that is a metal with typical metalic properties


negative ion

atomic radius

one-half of the distance between the center of identical atoms that are not bonded together.


a positively charged ion

electron affinity

the energy change that occurs when an electron is acquired by a neutral atom


a measure of the ability of an atom in a chemical compound to attract electrons


the formation of ions from solute molecules by the action of the solvent; any process that results in the formation of an ion


an atom or group of bonded atoms that has a positive or negative charge

ionization energy

the energy required to remove one electron from a neutral atom of an element

valence electrons

an electron that is available to be lost gained or shared in the formation of chemical compounds

chemical bond

a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together

ionic bonding

chemical bonding that results from the electrical attraction between large numbers of cations and anions

nonpolar covalent bond

A covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge


having an uneven distribution of charge

polar covalent bond

a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons

bond energy

energy required to break a chemical bond and form neutral isolated atoms

bond length

the distance between two bonded atoms at their minimum potential energy, that is, the average distance between two bonded atoms

chemical formula

A formula that indicates the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts

diatomic molecule

a molecule consisting of two atoms

double bond

a covalent bond in which two pairs of electrons are shared between two atoms

electron dot notation

an electron configuration notation in which only thevalence electrons of an atom of a particular element are shown, indicated by dotsplaced around the element's symbol

lewis structures

formulas in which atomic symbols represent nuclei and inner-shell electrons, dot-pairs or dashes between two atomic symbols represent electron paris in covalent bonds, and dots adjacent to only one atomic symbol represent unshared electrons

lone pair

A pair of electrons that is not involved in bonding and that belongs exclusively to one atom.

molecular compound

a chemical compound whose simplest units are molecules

molecular formula

a chemical formula of a molecular compound that shows the kinds and numbers of atoms present in a molecule of a compound


a neutral group of atoms held together by covalent bonds

multiple bond

a double or triple bond

octet rule

chemical compounds tend to form so that each atom, by gaining,losing, or sharing electrons, has an octet of electrons in its highest occupied energy level


the bonding in molecules or ions that cannot be correctly represented by a single Lewis structure

single bond

a covalent bond produced by the sharing of one pair of electrons between two atoms

structural formula

a formula that indicates the location of the atoms, groups, or ions relative to one another in a molecule and that indicates the number and location of chemical bonds

triple bond

a covalent bond in which two atoms share three pairs of electrons

unshared pair

a pair of electrons that is not involved in bonding and that belongs exclusively to one atom

formula unit

the simplest collection of atoms from which an ionic compound's formula can be established

ionic compound

composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal

lattice energy

the energy released when one mole of an ionic crystalline compound is formed from gaseous ions

polyatomic ion

a charged group of covalently bonded atoms


the ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire


the property of a metal that indicates that it can be bent and rolled into sheets


created by equal but opposite charges that are separated by a short distance

dipole dipole forces

polar molecules orient themselves so that oppositely charged ends are near eachother

hybrid orbitals

orbitals of equal energy produced by the combination of two or more orbitals on the same atom


the mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies

hydrogen bonding

the intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule

intermolecular forces

forces of attraction between molecules

london dispersion forces

intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles

molecular polarity

the uneven distribution of molecular charge

VSEPR theory

repulsion between the sets of valence-level electrons surrounding an atom causes these sets to be oriented as far apart as possible

metallic bonding

chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons

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