Selected Chemistry Vocabulary
acidification - when compounds are converted in a chemical reaction to become
more acidic; (also see ocean acidification).
atom - the defining structure of an element, which cannot be broken by any
chemical means.
atomic mass - (atomic weight) is the average mass of atoms of an element.
atomic number - number of protons in an element.
bond - an attraction between atoms brought about by a sharing of electrons between
two atoms or a complete transfer of electrons. Three types of bonds are ionic, covalent
and polar covalent.
bond order - in Lewis structures, the number of electron pairs shared by two
atoms.
buffer - a solution containing either a weak acid and its salt or a weak base and its salt,
which is resistant to changes in pH.
catalyst - substance that increases the rate of a chemical reaction, without being
consumed or produced by the reaction. Catalysts speed both the forward and reverse
reactions, without changing the position of equilibrium.
charge – electric charge refers to the properties of the of the subatomic particles that
determine their electromagnetic interaction; opposites attract. When an atom looses an
electron its charge becomes positive, when it gains an electron its charge becomes
negative.
chemical change - a dissociation, recombination, or rearrangement of atoms.
chemical bond - a strong attraction between two or more atoms. Bonds hold
atoms in molecules and crystals together. Electrons are given, taken or shared.
Ionic, covalent and metallic are some of the common types of chemical bonds.
chemical reaction - a chemical change that forms new substances; when within
a molecule, the chemical bonds are broken or rearranged.
cohesion - a measure of how well molecules stick or group themselves together
chemistry - the scientific study of matter, its properties and the interactions with other
matter and with energy.
compound - a compound is a material formed from elements chemically combined in
definite proportions by mass. For example, water is formed from chemically bound
hydrogen and oxygen.
Selected Chemistry Vocabulary
covalent bond - chemical link between two or more atoms in which electrons are
shared between them. In writing the structural formula a line shows it is a
covalent bond. Carbon typically forms covalent bonds leading to large complex
molecules of up to four bonds.
crystals - a homogenous solid formed by a repeating, three-dimensional pattern
of atoms, ions, or molecules and having fixed distances between them. Most
crystals are solids and formed from ionic bonds.
double bond - a bond where two electron pairs are shared between two atoms.
electron - a negatively charged component of an atom. Electrons exist outside of
and surround the atom’s nucleus. It contains very little mass compared with the
other parts of an atom.
electron shell - a set of atomic electrons grouped together by their energy
levels.
electronegativity - a property of an atom which increases with its tendency to attract
the electrons of a bond; a measure of the attraction an atom has for bonding electrons.
(essentially how greedy the element is for electrons) Bonds between atoms with
different electronegativity values are polar, with the bonding electrons spending more
time on average around the atom with higher electronegativity.
hydrogen bond - an especially strong dipole-dipole force between molecules;
are responsible for the unique properties of water and they loosely pin biological
polymers like proteins and DNA into their characteristic shapes.
incomplete octet - an atom with less than eight electrons in its valence shell.
ionic bond – a type of chemical bonding where electrons are completely
removed from one atom and given to another, meaning the atoms have an
electrical charge and are called ions. Unlike covalent bonds, ionic bond formation
involves transfer of electrons, and ionic bonding is not directional.
ionic compounds – tend to be hard and brittle, high melting point, poor
conductors of heat and electricity when solid, most are soluable in water, and
polar. All salts are ionic compounds.
ions – an electrically (+/-) charged atom or group of atoms formed by the loss or
gain of one or more electrons
isotope - atoms with the same number of protons but differing numbers of
neutrons. Isotopes are different forms of a single element.
Selected Chemistry Vocabulary
Lewis structure - electron dot structure; dot structure. A model pioneered by Gilbert N.
Lewis and Irving Langmuir that represents the electronic structure of a molecule by
writing the valance electrons of atoms as dots. Pairs of dots (or lines) wedged between
atoms represent bonds; dots drawn elsewhere represent nonbonding electrons.
mass number - an integer equal to the sum of the number protons and neutrons of an
atomic nucleus.
metallic bond – atoms share electrons with neighboring atoms and the electorns
are able to flow freely throughout the material.
metallic compounds – usually shiny, hard, good conductors of heat and
electricity and are malleable.
molecule - a collection of chemically bound atoms with characteristic
composition and structure.
neutron - is the particle in the atomic nucleus with mass = 1 and charge = 0.
nobel gases – typically only exist as a gas; all have eight electrons in their outer
valence; and low reactivity; rarely bond with other atoms.
nonpolar bond - a type of chemical bond which has no positive or negative
'ends'.
nucleus (plural, nuclei) - means center. In chemistry, nucleus refers to the positively
charged center of the atom protons and neutrons.
octet rule - a guideline for building Lewis structures that states that atoms tend
to gain, lose, or share valances with other atoms in a molecule until they hold or
share eight valance electrons. Elements strive for 8 electrons to be stable, or
“happy”.
organic compound – one containing carbon
period – within the periodic table each column; with the exception of metals is a period.
Elements within the same column have the same number of valence electrons and
similar chemical characteristics.
polar bond - a covalent bond between two atoms where the electrons forming
the bond are unequally distributed. This causes the molecule to have a slight
electrical dipole moment where one end is slightly positive and the other is
slightly negative.
polar molecule – unequal sharing occurs, contains polar bonds where the sum
of all the bond's dipole moments is not zero.
Selected Chemistry Vocabulary
product - a substance that is formed as the result of a chemical reaction.
proton - a component of an atomic nucleus with a defined mass of 1 and a
charge of +1.
reactant - the substance that is consumed during a chemical change.
skeletal formula – notation that shows the number and kinds of atoms in a
molecule and how the atoms and bonds in the molecule are arranged.
structural formula - covalent bonds are represented by a line drawn between
the symbols of the bonded atoms.
valance electrons – the electrons found in the outermost shell of an atom, which are
involved in chemical bonding; those with only one or two electrons tend to give them
away when bonding; those with four to seven tend to share or take electrons when
bonding.