ACCURACY
comparison to an accepted standard.

ACTIVATION ENERGY
is the minimum energy required to start a chemical reaction

ALPHA PARTICLES
are helium nuclei (no electrons) produced in nuclear reactions. They are helium ions, He+2.

ATOM
is the smallest particle of a chemical element.

ATOMIC MASS
is the average mass of the isotopes of an element. It is the decimal number on the periodic chart. It depends upon both the isotopes' masses and the amount of each isotope present.

ATOMIC NUMBER
is the number of protons in the nucleus of an atom. It is the whole number on the periodic chart. It is also the number of electrons in a neutral atom (where protons = electrons).

BETA PARTICLES
are electrons produced in nuclear reactions. They are Electrons.

BOND COVALENT
is the sharing of electrons. There is no rip off because the ionization energies of the atoms are not drastically different in magnitude. The result is neither atom is strong enough to remove the electron from the other atom. (Like two kids of equal strength trying to take a ball away from each other. They both can only hold on to it, neither succeeding in taking it and thus they are bonded).

BOND IONIC
is formed by electron transfer (the rip off). An element whose electrons are loosely held (first and second columns of chart) surrenders its outer electron(s) to an element with high ionization energy (that therefore has a high electron affinity). The latter are the right hand side of the chart (like the halogens). When the transfer is completed, we have ions produced. The unlike charges of the ions holds them together electrically. Hence, the ionic bond. Elements from opposite sides of the chart have very different ionization energies, so that one atom is strong enough to rip off electrons from the other.

CANAL RAY TUBE
showed that ions are produced by electron bombardment. The simplest positive ion, H+1, is the PROTON.

CHEMICAL EQUATIONS
show what reacts with what, what new substances are formed, and their reacting ratios.

CHEMICAL FORMULAS
show which elements are present and their ratios.

CHEMICAL PROPERTIES
are such things as reactivity, oxidation states, flammability, and corrosiveness.

CHEMICAL SYMBOLS
are abbreviations for the elements.

COMPOUND
is two or more elements chemically combined.

DALTON'S LAW of DEFINITE PROPORTIONS
states that every compound has a definite composition by weight. Ah, the formulas.

De BROGLIE'S HYPOTHESIS
states that electrons around atoms are in wave formation.

DENSITY
is equal to mass/volume.

ELECTRON
is a basic particle whose charge is -1 and whose mass is 1/1837 g/mol (amu).

ELECTRONS
have both wave and particle properties.

ELEMENT
is the simplest form of matter.

EMPIRICAL FORMULA
is the simplest whole number ratio of elements in a compound, ie CH2.

ENDOTHERMIC REACTION
takes more energy to start it than it gives back. It has a positive DH. It needs energy to keep it going. An example is cooking. (Chippers a baking!)

ENTHALPY
is the heat of reaction, either exo- or endothermic. It is measured either in kilocalories/mole or kilojoules/mole.

EXOTHERMIC REACTION
gives out more energy than was put in to start the reaction. It has a negative DH. It keeps going after it is started. An example is a fire.

GAMMA RAYS
are electromagnetic radiations beyond the X-rays in frequency. They are usually produced in nuclear reactions.

HETEROGENEOUS
materials are not uniform throughout.

HOMOGENEOUS
materials are the same throughout. All solutions are homogeneous.

HYDROGEN BOND
is a special situation that exists between the hydrogen atom in one molecule (like water) and the oxygen atom in another molecule (like another water molecule). This bond is ten times weaker than the covalent bond, and ten times stronger than the van der waals force. The hydrogen bond caused water to have its unusual properties of high boiling point, high melting point, high surface tension, and its formation of the six- sided ring structure in ice. The latter causes water to expand upon freezing, become less dense, and float in water.

ION
is a charged atom or group of atoms. Ionization is caused by a gain or loss of electrons. A loss leaves a positive charge, a gain leaves a negative charge.

IONIZATION ENERGIES SUNSEQUENT
remove more electrons. The factors that determine the ionization energies are: distance from the nucleus (inverse square law) whether the orbital is filled or half-filled whether there is a noble gas structure the shielding effect of electrons in lower orbitals the ratio of protons to remaining electrons (guards to prisoners ratio)

IONIZATION ENERGY
is the minimum energy needed to remove an electron from an atom.

IONIZATION ENERGY FIRST
takes off the first (outermost) electron.

IONS NEGATIVE
are those which have gained electrons and therefore have more negative charges than positive charges (protons).

IONS POSITIVE
are those which have lost electrons and therefore have fewer negative charges than positive charges (protons).

ISOTOPES
are the same elements with different mass numbers. This is caused by having a different number of neutrons in the nucleus.

LAW of CONSERVATION of ENERGY
states that energy cannot be destroyed nor created, but only changed in form. Ex. heat --> electricity --> light, etc.

LAW of CONSERVATION of MATTER
states that matter cannot be created nor destroyed, but only changed in form. For example matter and mass can be interchanged.

LAW of MULTIPLE PROPORTIONS
shows that some compounds have formulas that are whole number multiples of atoms Ex. NO2, N2O4; H2O, H2O2; FeO, Fe2O3.

LIGHT
has both wave and particle properties.

MASS NUMBER
is the relative mass of the isotopes compared to that of Carbon-12 whose mass is 12.0000 g/mol. It is not shown on the periodic chart. It is also equal to the sum of protons + neutrons inasmuch as protons and neutrons each have an atomic mass of 1 g/mol (amu - atomic mass unit).

MASS OF AN ELECTRON
and ions were determined by using the charge/mass ratio and the actual charge (Millikan). The electron's mass is 10-31kg.

MASS SPECTROMETER
is a refined Sir JJ Tube in which the masses of particles, ions, and isotopes are measured. It separates isotopes according to charge and mass.

MELTING AND BOILING TEMPERATURES
are caused by the van der waals interaction. Solids melt and liquids evaporate when the van der waals forces between molecules are broken.

METHODS OF IONIZATION
include photoionization (using light energy like ultraviolet rays), thermionic emission (using high temperature to boil off electrons), and electron bombardment (kick 'em out with a stream of electrons from another source).

MILLIKAN OIL DROP EXPERIMENT
measured the actual charge on an electron.

MOLECULAR FORMULA
shows the actual number of atoms in compound. Ex. C2H4

MOLECULAR MASS
is the sum of the atomic masses of all the atoms in a molecule.

MOLECULE
is the smallest particle of a chemical compound. It contains two or more atoms.

NEUTRON
is a basic particle whose charge is 0 and whose mass is 1 g/mol (amu).

NUCLEON
refers to the particles in the nucleus-- Protons and Neutrons.

ONLY ELECTRONS FLOW
to produce ions. The protons are deep down in the nucleus and stay there. (Except in nuclear reactions, but that's another story ). So electrons are either added or subtracted to make ions.

ORBITALS
are the probability distributions of where electrons may be found in their atoms, s -orbitals are spherical, p - orbitals are dumbbell shaped.

OXIDATION NUMBERS or VALENCES
are the number or electrons lost, gained or shared in a chemical reaction. Free elements have zero as an oxidation number.

PAULI EXCLUSION PRINCIPLE
states that no two electrons may have the same quantum numbers. Only two electrons may occupy an orbital, but they must have opposite spins.

PERCENTAGE COMPOSITION
can be found by totaling the atomic masses of the atoms in the formula, dividing each mass by the total, and changing the results to %-age.

PERIODIC TABLE
(first worked out by Mendeleev in 1869) is organized by the regularly repeating pattern of chemical properties of the elements. Each column is a family of elements having similar properties. The properties are a periodic function of the atomic numbers. Atomic number is symbolized "Z". The table is based on the electron configuration of the atoms.
The first column is the Alkali metals, they react vigorously with water to give hydrogen gas. They are lithium, sodium, potassium, rubidium, cesium, and francium. Francium is a man-made radioactive element.
The second column is the Alkaline Earth elements. They are active, but much less so than the previous column.
The transition metals have electrons filling d sublevels. They, used alone or as alloys, are our principal structural metals.
An alloy is a mixture of metals, a solid solution.
The seventh column is the Halogens (salt formers). These are the deadly fluorine, chlorine, bromine, iodine, and astatine. Astatine is a man-made radioactive element.
The eighth column is the noble gases. These loafers are most inactive. Only extreme measures can make them react. They are helium, neon, argon, krypton, xenon, and radon.
The Lanthanides and Actinides are the two rows at the bottom of the chart. Each of these two series fit into one spot (Lanthanides in the the lanthanum place, and Actinides into the actinium place). The reason for this is because electrons are being added to the 4f sublevel instead of to a sublevel of the sixth or outer level. Hence they all have the same oxidation state (valence) and similar properties.

PHOTOELECTRIC EFFECT
is the emission of electrons from metal when the metal is struck by light.

PHYSICAL PROPERTIES
are such things color, density, hardness, ductility, malleability, solubility, heat conduction, electrical properties, melting and boiling point.

POSITRONS
are electrons with a +1 charge. They are found in cosmic rays and in nuclear reactions. They are antimatter. When they meet an electron there is complete annihilation to give pure energy in the form of gamma rays. This is total matter and energy conversion by E = mc2.

PRECISION
gives consistent results. (Something can be precisely inaccurate.)

PRINCIPAL QUANTUM NUMBER, n
gives the energy of the orbital. This is determined by the distance of the electron from the nucleus.

PROBLEM SOLVING
can best be reviewed by working the examples in your chemistry notebook. Try them first without peeking at the solutions. Then spend your time on those that you failed to solve.

PROTON
is a basic particle with a charge of +1 and a mass of 1g/mol (amu).

QUANTUM NUMBERS
describe the distance, shape, and orientation of the electronic orbitals.

RATIO OF THE ATOMIC DIAMETER TO THE NUCLEAR DIAMETER is 10to the 5th. The volume ratio is 10to the 15th. It would require 10to the 15th nuclei to fill an atom! -- "The flea in Yankee Stadium".

RECTILINEAR PROPAGATION
is the principle that electromagnetic radiations like light travel in straight lines.

REGELATION
is the process of melting ice by pressure. Inasmuch as water expands upon freezing, pressure will reverse the process, forcing water to melt. Then when the pressure is released, the water re-freezes (re-gells).

SCHROEDINGER'S WAVE EQUATION
explains the shapes of the orbitals of the electrons around an atom. They are probability distributions. That is, there is a probability of finding an electron's position in a "cloud" around an atomic nucleus. The electron appears to be "spread out" as it orbits, filling its cloud.

SECOND QUANTUM NUMBER, l
describes sublevels. The sublevels are called, s, p, d, f. s orbitals are spherical in shape. p orbitals are dumbbell shaped.

SIGNIFICANT DIGITS
those that can be accurately measured. An answer can have no more significant digits than the least number of them in the data.

SIR JJ THOMPSON'S "J"
tube determined the charge to mass ratio of electrons and ions. This led to the discovery of isotopes.

SIZE OF THE ATOM
can be measured by oil slick experiments or by calculating how many atoms lie along the side of a cube of a known number of moles of atoms.

SIZE OF THE NUCLEUS
was measured by Lord Rutherford using the scattering patterns of alpha particles passing through gold foil. It is 10-15 meter.

SPECTROSCOPY
is the analysis of the lines of light emitted from excited atoms as the electrons drop back through their orbitals. These lines give the energy and distances of the electronic orbitals.

THE MOLE
is the number of atoms in the atomic mass of an element or the number of molecules in the molecular mass of a compound. It = 6.02 X 10 to the 23 atoms or molecules.

THERMIONIC EMISSION
is the boiling off of electrons from heated metals. It gives a source of electrons for cathode ray tubes.

VAN DER WAALS FORCES
are weak interactions between MOLECULES. (Note: chemical bonds are the forces between ATOMS in a molecule whereas van der waals forces are between MOLECULES). These weak forces are caused by the attraction between protons in one molecule and electrons in an adjacent molecule. Because of the greater distance between the particles in one molecule and another, van der waals forces are only 1/100 as strong as the covalent bond.

WRITING and BALANCING
equations should be reviewed in your Big Chem notebook. Try them with the solutions covered, then check your results.

X-RAYS
are electromagnetic radiations above the Ultra Violet in frequency that are produced when electrons strike a metal target. They are used to determine the atomic number of elements and the structure of crystals.