•  Mr. Bannister's   CHEM IA WORD WALL

The following terms have been deemed "important" and additional time should be spent to fully understand and comprehend their use and definitions.  Use them at home, at school, and with your friends to illustrate your clearly articulated and intelligent thoughts!!

Chemistry - the study of matter and the changes they undergo

Chemical - anything with a definit composition

Matter - anything that has mass and takes up space

Mass - the amount of matter an object contains

Density - how much mass is in a given space (volume)

Accuracy - the "exactness" of a value (i.e. the bullseye)

Precision - the "grouping" of data points or values

Reproducibility - a measure of efficiency in data collection.  Obtaining similar results repeatedly

SigFigs - (a.k.a Significant Figures or Significant Digits) the total number of digits of KNOWN certainty in a measurement.

Dimensional Analysis - A mathematical ratio of equivalent values used to convert from unit to unit between similar quantities (i.e. mass -- mass, volume -- volume, quantity -- quantity, etc.)

Conversion Factor - the "heart of the problem"; the value that relates quantities for comparison and conversions for use in dimensional analysis (the factor-label method).

Mole -a value used to quantify "how much" of a substance we are dealing with.  1 mole of anything contains 6.022x10^23 particles.

Molar Mass (a.k.a. formula mass) - the mass of one mole of a compound / molecule / element.  This value acts as our conversion factor to bridge the gap between mass and moles.

Atomic Number - The number of protons in an atom (and if neutral, the number of electrons).  This value can be thought of as an atom's social security number, in that is an identifying value that cannot be changed without changing the identity of the atom.

Atomic Theory - The theory that all matter is composed or indivisible particles (atoms).  This theory has been upgraded and perfected through the help of many contributing minds over the past several hundred years.

Proton - a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign.

Electron - a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.

Neutron - a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen

Electron Configuration - The distribution of electrons in an atom or molecule.

Electron Shielding - describes the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell.

Quantum Number - A number, usually considered in a set of four, that indicates the location and relative energy of a particular electron in an atom or molecule.

Ionic Compound - a chemical compound in which ions are held together in a lattice structure by ionic bonds.  A "charged attraction"

Covalent Molecule - a relatively strong structure composed of two nonmetals that combine individual orbitals to form one shared space called a molecular orbital.  These bonds are held together by "Electron Sharing"

Lewis Dots - diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule

Balanced Chemical Reaction - An equation that shows a chemical reaction and illustrates the Law of Conservation of Mass.  Not only the same types of atoms from the reactants appear on the product side, but also the same quantities.

Acid / Base Neutraliztion Reaction - A special type of double displacement reaction in which the acid H+ reacts with and neutralizes (or is neutralized by) the basic hydroxide (OH-).  Products of these reactions consist of water and a salt.

Stoichiometry - The ratios of products / reactants in a chemical reaction denoted using a chemical equation.  These "conversion factors" allow one to calculate quantities within the reaction when given other values.

Stoichiometric Coefficient - The coefficient preceding the reactants / products in a balanced chemical reaction.

Limiting Reatant - The reactant in short supply; controls the reaction; when this runs out, the reaction ceases/halts.

Excess Reactant - The reactant in a particular chemical reaction that will not run out; more than enough to complete the reaction.

Percent Composition - The ratio of the actual yield over the theoretical (in percent form).

Theoretical Yield - The quantity that stoichiometric calculations tells us we should get (in a perfect world).

Actual Yield - the ACTUAL quantity obtained when actually completing a reaction.  This value is always less than the theoretical, as no reaction is more than 100% efficient (or even a perfect 100%).

The Mole - A counting unit used by chemists to quantify "small things" (particles, atoms, molecules, etc.)

Avogadro's Number - 6.022x10^23... A conversion factor that enables us to go between moles and particles (atoms, molecules, ions, compounds, etc.).  A mole contains 6.022x10^23 particles)