A process which involves substitution of one ion, either
anion, for another of the same charge when a solution containing
ions is passed into a molecular network having either acidic or basic substituent groups
which can be readily ionized. The ions in the solution attach themselves to the network, replacing
the acidic or basic groups.
Many insoluble substances which have an interlocking molecular structure (or cage structure) can
act as ion exchangers.
Zeolites, the first ion exchange materials, were used for water softening.
Other uses of ion-exchange include: rare-earth separations,
acid removal, elimination of ionic impurities (i.e. demineralization), etc. Soil exhibits
ion-exchange activity. This has an important bearing on fertilizer application.
A bond that is formed by the transfer of electrons from
one atom to another. As a result, the positively charged ion is attracted to the
negatively charged ion by coulombic attraction.
The strong attractions within ionic solids are responsible for their high
melting points. For example, the melting point of
the ionic compound sodium chloride, NaCl, is 801 oC.
Ionic bonded solids such as NaCl do not conduct electricity. This is
because the electrons in an ionic compound do not move through the ionic
structure like that in metallic bonding.
The smallest unit in ionic compounds is a
formula unit as ionic compounds do not exist as discrete entity but as ions.
The process which involves the removal of an electron from an atom.
Ions are electrically charged species. They are
formed when a neutral atom either gains or lose electrons. An ion
is negatively charged if the atom gains electron(s). It is positively
charged if the atom loses electron(s).
(Note: Ions can also be formed by a group of atoms either gains
or loses electrons.)
The prehistoric period succeeding the
Bronze Age, marked by teh introduction of iron
meturllurgy. In Europe this is around 8th century B.C.
Species that have the same number of
electrons. For example, Na+ and Ne are isoelectronic.
Isotopes of an element are atoms having the
same atomic number but different numbers of neutrons in their nuclei.
Therefore, they have different masses.
For example, 12C has 6 neutrons, 13C has 7 neutrons.
This is energy of motion. It depends on the
object's mass and velocity. The mathematical equation that relates kinetic energy
to mass and velocity is
K.E. = ½mv2
The Lanthanide series of inner transition elements includes
cerium, atomic number=58 through
lutetium, atomic number=71. They are also called the
Law of Chemical Periodicity
Properties of the elements are periodic functions
of atomic number. That is, when the elements are arranged by order of atomic number, within a
group their properties are similar to one another.
Law of Conservation of Energy
states that energy can be neither
created nor destroyed. It can only be changed from one form to another
(ie - from
kinetic energy to
potential energy or vice versa).
Law of Conservation of Mass
states that mass is neither
created nor destroyed, therefore, atoms are neither created nor destroyed.
Gilbert N. Lewis
(1875-1946). Lewis made numerous
outstanding contributions to chemistry. Students learning chemistry
remember him by his contribution in making the concept of valence
electrons easier to understand by using the electron-dot symbols
to represent valence electrons as dots.
Lewis electron-dot symbol
The symbol of an element
surrounded by one to eight dots to represent the valence electrons of an
atom or ion of the element.
Various mineral and industrial forms of calcium oxide. Two forms of limes
are quicklime, calcium oxide, CaO, and
slaked lime, calcium hydroxide (Ca(OH)2).
In ancient process, the Romans mixed slaked lime with sand to produce mortar for use in construction.
The total number of
neutrons in the nucleus of an atom is the
mass number.It is also the atomic mass of the atom rounded to the nearest
two metals such as sodium aluminum hydride, NaAlH4, or
a metal and a nonmetal such as lithium borohydride, LiBH4.
Hydrides are hazardous materials which may catch on fire when rubbed or agitated. They are
powerful reducing agents used in chemcial reactions.
They are also employed as a sources of hydrogen and as
This is bonding of metal atoms where positive metal ions are in a
three-dimensional arrangement and the valence electrons are able to move freely
over the entire structure of the metal. Thus metals can conduct electricity.
This type of bonding is different from
ionic bonding and
It is the group of elements that are to the left of the diagonal line on the
A commercially available pyrophoric alloy of cerium and
a mixture of several rare-earth metals. It will ignite when exposed
to heat and friction. It is used in lighter flints.
Any sample of
matter that is not an
compound. It is any matter
consisting of two or more substances
physically combined. The composition of a mixture, unlike that of a
has no particular proportion.
The mass, in grams, of one mole
of any substance. For example,
The volume of one mole of gas at
STP is 22.4 liter/mole.
A mole is a counting unit, much like counting by a dozen.
A dozen items equal 12 items. A mole items equal
Avogadro's number , NA , or 6.02214 x 1023 items.
It is used to count microscopic particles.
One mole of an element is NA atoms.
One mole of a compound is NA molecules.
A compound formed by two or more atoms joined
together by covalent bonds.
The chemical formula that gives the actual
number of atoms of each kind present in a molecule of the substance.
The sum of the atomic masses of all atoms in one
molecule of a compound.