Glossary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Allotrope: Different physical forms of the same element.
Atom: The smallest indivisible particle of an element.
Atomic number: Identifies the element and tells you the number of protons in an atom of an element.
Atomic radius: The distance between the center of the nucleus of the atom and the outer edge of the atom.
Bond: The attractive force that attaches one atom to another.
Bond Angle: The angle between two bonds in a molecule.
Bonding Pair: An electron pair that bonds on another atom to a central atom in a molecule.
Compound: A pure substance made from two or more different elements.
Covalent bond: A bond between two nonmetallic atoms that obtain their full valence level by sharing electrons.
Covalent compound: A compound made of two or more different nonmetallic elements.
Covalent molecule: A molecule made of nonmetallic elements.
Dipole-Dipole Force: A type of intermolecular force
that exists only between polar molecules. A dipole-dipole force is the
attraction of the 
part
of one molecule and the 
part
of a neighbouring molecule.
Dispersion Force (London Force): Dispersion forces exist
between all small covalent molecules. Electrons within the molecule momentarily
shift away from one side of the molecule, setting up a momentary temporary
dipole. The attraction between the and
of
the temporary dipoles is called the dispersion force. This is an attractive
force!
Electron: a negatively charged particle in the atom; it has negligible mass.
Electronegativity: A measure of how well an atom will attract a shared electron pair to itself.
Electron Affinity: The amount of energy released when an electron is added to a neutral gaseous atom.
Electron cloud: a region of space surrounding the nucleus of an atom. This region is the volume of space where an electron is likely to be found. The electron cloud comprises most of the volume of an atom.
Electron Configuration: A shorthand way of showing the location of electrons in an atom. Example: 1s2 2s2 2p5 is the electron configuration for the element Flourine.
Electron Sea: The valence electrons in a metal are delocalized and are free to flow in the "electron sea". It is this electron sea that makes up the metallic bond.
Energy Level: A certain volume of space around the nucleus in which an electron is likely to be found. Energy levels start at level 1 and go to infinity.
Element: A building block of matter. If a substance is an element, it can be found on the periodic table.
Excited State: An electron has absorbed energy and moved to a higher than normal energy level orbital.
Family: A family of elements is a group of elements on the periodic table. A family of elements appears in a column. The elements within the same family have many characteristics in common.
Ground state: Electrons are normally found in the lowest available energy orbitals.
Group: A family of elements is sometimes given a group number. The group number appears at the top of the column of elements.
Hydrogen Bond: Dipole-dipole forces are called hydrogen bonds when a polar molecule contains H atoms that are bonded to very electronegative elements like N, O or F.
Intermolecular forces: Attractive forces between molecules.
Ion: Atoms or groups of atoms that carry a charge.
Ionic bond: An ionic bond joins two ions together. The metallic element has lost an electron to become a positive ion and the nonmetallic element has picked up the lost electron(s) to become a negative ion. The attraction between the unlike charges is known as the ionic bond.
Ionic compound: A compound made of ions. Usually ionic compounds are made of a metal and a nonmetal. There are exceptions to this, for example, ammonium nitrate is an ionic compound that does not contain a metal. The ammonium ion though is a polyatomic positive ion.
Ionic radius: Ionic radius is the distance between the center of the nucleus and the outer edge of the ion.
Ionization energy: The amount of energy needed to remove an electron from a neutral gaseous atom.
Isotopes: Atoms of the same element that have the same atomic number but different mass numbers due to the differing number of neutrons.
Lewis Structure: A short hand way of showing the valence electrons. Valence electrons are shown as dots; in a molecule, the bonds are shown as dashes.
Line Spectrum: the collection of lines of light of various colors (frequencies) that is obtained after passing light through a prism. The light used to pass through the prism consists only of a few wavelengths. If natural light is passed through a prism, a continuous spectrum is observed.
London Force: Another name for a dispersion force.
Lone Pair: An electron pair on the central atom of a molecule. This long pair does NOT bond on another atom.
Mass Number: Gives the number of protons and neutrons in the atom.
Metals: Those elements that attract to a magnet. They are located on the left side of the periodic table.
Metallic bond: The attractive force that holds particles of a metal together. The valence electrons of the metal are free to flow throughout the crystal.
Molecular dipole: Polar covalent molecules have a molecular
dipole; they have a and
a side
as a result of polar bonds and asymmetrical shape.
Monatomic ion: An atom that carries a charge.
Network solids: Giant arrangements of matter in which atoms are covalently bonded together in a continuous two or three dimensional array.
Neutron: A particle with no charge that is found in the nucleus of the atom. A neutron has a mass of 1 u. The number of neutrons is equal to the mass number minus the atomic number.
Noble Gas: This is the family of elements in Group VIIIA of the periodic table shown. Noble gases are stable elements because they have a full valence level.
Nonmetal: An element on the left side of the periodic table that does not show characteristics of a metal. Nonmetals will not be attracted to a magnet.
Nonpolar covalent bond: If the electron pair that is shared between two atoms spends equal time with each atom, then the electron pair is equally shared and we have a nonpolar covalent bond.
Nucleus: The central core of the atom. The nucleus contains the protons and neutrons. The nucleus comprises most of the mass of the atom but little volume of the atom.
Octet Rule: All atoms tend to gain, lose or share electrons to become like the nearest noble gas in electron population.
Orbital: A volume of space in which it is highly likely to find an electron. Orbitals can be of different shapes: s, p, d, and f.
Percent Ionic Character: A way to express the degree of sharing of electrons between two atoms involved in a bond. Equal sharing of electrons corresponds to zero percent ionic character.
Period: A row (left to right) of elements in the periodic table.
Periodic Table: A special arrangement of the elements in order of increasing atomic number.
Physical properties: Properties that can be recorded without changing the substance. Examples: color, smell, texture, melting point, boiling point, density, mass.
Polar covalent bond: If the electron pair that is shared between two atoms spends more time with one atom than the other, then we have a Polar covalent bond.
Polar Molecule:
A covalent molecule that has a and
a side
as a result of polar bonds and asymmetrical shape.
Polyatomic Ion: A group of atoms that carry a charge.
Proton: A particle with +1 charge that is found in the nucleus of the atom. A proton has a mass of 1 u. The atomic number of the element tells you the number of protons in the atom.
Resonance structures: More than one version of a lewis structure can be drawn for some molecules. The different versions are called resonance structures.
Semimetal: Those elements on the periodic table that show some properties of metals and of nonmetals. These elements are around the "staircase".
Spectral Line: one line in a line spectrum.
Structural Formula: A Lewis Structure of a covalent molecule that only shows the bonding pairs of electrons. No dots are present.
Valence Electron: The electron(s) in the outermost level of the atom.
Valence Level: The outermost level of the atom that is occupied by an electron.
van der Waals forces: Attractive forces between molecules.
VSEPR theory: The Valence Shell Electron Pair Repulsion Theory. This theory is used to predict shapes of cavalent molecules.
