Glossary of Terms

Ion exchange
A process which involves substitution of one ion, either cation or 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.
Ionic bond
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.
Ionization
The process which involves the removal of an electron from an atom.
Ions
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.)
Iron Age
The prehistoric period succeeding the Bronze Age, marked by teh introduction of iron meturllurgy. In Europe this is around 8th century B.C.
Isoelectronic
Species that have the same number of electrons. For example, Na⁺ and Ne are isoelectronic.
Isotope
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.
Joule
The SI unit of energy.

1 joule = 1 kg m²s^-2 = 4.184 cal
The Kelvin scale
The lowest possible temperature on the Kelvin scale is 0 K, where

K = ^oC + 273.15

Therefore, absolute zero is -273.15 ^oC.
Kinetic energy
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
Lanthanides
The Lanthanide series of inner transition elements includes cerium, atomic number=58 through lutetium, atomic number=71. They are also called the rare earths.
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.
Lime
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.
Mass number
The total number of protons and neutrons in the nucleus of an atom is the mass number.It is also the atomic mass of the atom rounded to the nearest whole number.
For example,

Element Mass number

Carbon (atomic mass = 12.011 amu) 12

Copper (atomic mass = 63.546 amu) 64
Matter
Matter is any object or material that occupies space. The quantity of matter is measured by its mass. All the materials we see around us are examples of matter.
Melting point
The temperature at which a substance undergoes a phase transition from a solid to a liquid.
Mercaptans
A sulfur-containing organic compound that has associated with it foul odors. Mercaptans can be removed by adsorption process and "copper-sweetening" process.
Metal hydride
A compound formed by combination of hydrogen either with:
- a single metal such as lithium hydride, LiH,
- 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 catalysts.
Metallic bond
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 covalent bonding.
Metalloids
See semimetals.
Metals
Metals generally have the following properties:
- high luster,
- conduct electricity,
- conduct heat,
- malleable, and ductile,and
- high densities.
It is the group of elements that are to the left of the diagonal line on the periodic table.
Misch metal
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.
Mixture
Any sample of matter that is not an element or compound. It is any matter consisting of two or more substances physically combined. The composition of a mixture, unlike that of a substance, has no particular proportion.
Molar Mass
The mass, in grams, of one mole of any substance. For example,

Substance Molar Mass

carbon 12.011 g/mole

H₂ (g) 2.016 g/mole
Molar Volume
The volume of one mole of gas at STP is 22.4 liter/mole.
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 , N_A , or 6.02214 x 10²³ items. It is used to count microscopic particles.

One mole of an element is N_A atoms.

One mole of a compound is N_A molecules.
Molecule
A compound formed by two or more atoms joined together by covalent bonds.
Molecular formula
The chemical formula that gives the actual number of atoms of each kind present in a molecule of the substance.
Molecular mass
The sum of the atomic masses of all atoms in one molecule of a compound.

Element	Mass number
Carbon (atomic mass = 12.011 amu)	12
Copper (atomic mass = 63.546 amu)	64

Substance	Molar Mass
carbon	12.011 g/mole
H₂ (g)	2.016 g/mole

This page is part of the BCIT Chemistry Resource Center website.

All contents copyrighted © 1997 - 2004
 Chemistry Department
British Columbia Institute of Technology, Burnaby, B.C. Canada.
All Rights reserved

Ion exchange

Ionic bond

Ionization

Ions

Iron Age

Isoelectronic

Isotope

Joule

The Kelvin scale

Kinetic energy

Lanthanides

Law of Chemical Periodicity

Law of Conservation of Energy

Law of Conservation of Mass

Gilbert N. Lewis

Lewis electron-dot symbol

Lime

Mass number

Matter

Melting point

Mercaptans

Metal hydride

Metallic bond

Metalloids

Metals

Misch metal

Mixture

Molar Mass

Molar Volume

Mole

Molecule

Molecular formula

Molecular mass