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CHEM 120 FINAL EXAM | QUESTIONS WITH CORRECT ANSWERS| LATEST UPDATE 2025|A+ RATED, Exams of Chemistry

CHEM 120 FINAL EXAM | QUESTIONS WITH CORRECT ANSWERS| LATEST UPDATE 2025|A+ RATED

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2024/2025

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CHEM 120 FINAL EXAM | QUESTIONS WITH CORRECT
ANSWERS| LATEST UPDATE 2025|A+ RATED
molecular mass (molecular weight)
the sum of the atomic masses, in atomic mass units, of all the atoms in
the formula of a compound
empirical formula
a chemical formula showing the ratio of elements in a compound
rather than the total number of atoms
Avogadro's number (Mole)
6.02 x 10^23
proton
A subatomic particle that has a positive charge and that is found in the
nucleus of an atom
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CHEM 120 FINAL EXAM | QUESTIONS WITH CORRECT

ANSWERS| LATEST UPDATE 2025|A+ RATED

molecular mass (molecular weight) the sum of the atomic masses, in atomic mass units, of all the atoms in the formula of a compound empirical formula a chemical formula showing the ratio of elements in a compound rather than the total number of atoms Avogadro's number (Mole) 6.02 x 10^ proton A subatomic particle that has a positive charge and that is found in the nucleus of an atom

neutron A subatomic particle that has no charge and that is found in the nucleus of an atom electron A subatomic particle that has a negative charge and orbits the nucleus valence electron an electron that is found in the outermost shell of an atom mole ratio a conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction ion An atom or group of atoms that has a positive or negative charge.

an ion that appears on both sides of an equation and is not directly involved in the reaction acid compound that forms hydrogen ions (H+) in solution base a compound that produces hydroxide (OH-) ions in solution Lewis structure a diagram of a molecule showing how the valence electrons are arranged among the atoms in the molecule. dashes are used to represent bonds

  1. Draw skeletal structure.
  2. Check number of valence electrons needed for each atom.
  3. Add double bonds if necessary.
  4. Check total charge on molecule and total number of electrons.
  5. Check for atoms that may have an expanded octet.

Bohr Model model of an atom that shows electrons in circular orbits (shells) around the nucleus Electronegativity A measure of the ability of an atom in a chemical compound to attract electrons Core charge The number of protons subtracted by the number of inner shell electrons partial charge the unequal sharing of electrons which results in a slight negative or positive charge valence electrons - nonbonding electrons - (electron pull of atom x bonding electrons of atom) = partial charge on atom "a"

dispersion forces attractions between molecules caused by the electron motion on one molecule affecting the electron motion on the other through electrical forces; this is the weakest intermolecular force limiting reagent any reactant that is used up first in a chemical reaction; it determines the amount of product that can be formed in the reaction exothermic reaction A reaction that releases energy in the form of heat. Occurs when bonds are formed. Result in a negative ΔH endothermic reaction A reaction in which energy is absorbed. Occurs when bonds are broken. Result in a positive ΔH bond order

the number of bonds between atoms: 1 for a single bond, 2 for a double bond, and 3 for a triple bond (# bonding electrons - # antibonding electrons)/ bond length the average distance between the nuclei of two bonded atoms bond strength the energy required to break the bond(s) of molecules. It depends upon two things; the number of bonds (triple>double>single) and the type of bonds (Covalent (Intra)>Ionic>Hydrogen (Inter)>London dispersion) bond angle the angle formed by two bonds to the same atom Two domains of electrons= 180° Three domains of electrons= 120° Four domains of electrons= 109.45°

electron spin A property of the electron that makes it behave as though it were a tiny magnet. The electron behaves as if it were spinning on its axis; electron spin is quantized. diamagnetic paired electrons paramagnetic unpaired electrons electron shells (energy levels) Regions of space that consecutively surround the nucleus of an atom. electron orbitals

volumes of space surrounding the atomic nucleus where electrons are likely to be found electron subshell a region of space within an electron shell that contains electrons that have the same energy electron suborbitals s, p, d, f s orbital can hold 2 electrons p orbital can hold 6 electrons d orbital

Oxidation Number Rules

  1. Each atom in a pure element = 0
  2. Monotonic ions = charge on the ion
  3. When combined with another element, F = -
  4. Oxygen = - Exceptions:
  • when combined with fluorine = positive oxidation #
  • in peroxides (Na2O2) and superoxides (KO2) = -1, -0.
  1. Hydrogen = +
  2. Neutral compounds - sum of oxidation #s = 0
  3. Polyatomic ions - sum of oxidation #s = ion charge
  4. Group 1A = +1 (unless in elemental form)
  5. Group 2A = +2 (unless in elemental form) oxidation loss of an electron reduction gain of an electron

oxidation agent electron acceptor reduction agent electron donor redox reaction A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction. covalent bond A chemical bond that involves sharing a pair of electrons between atoms in a molecule polar covalent bond A covalent bond in which electrons are not shared equally

dipole moment electronegativity differences cause partial charges which cause bond dipoles which cause dipole moments dipole moment= magnitude the two charges x distance between the two charges boiling point The temperature at which a liquid changes to a gas. Determined by the strength of intermolecular forces. The stronger the intermolecular forces are, the higher the boiling point. atomic number the number of protons in the nucleus of an atom mass number the sum of the number of neutrons and protons in an atomic nucleus atomic mass

The average mass of all the isotopes of an element Molecular Nomenclature Rules

  1. Use the name of the cation followed by the name of the anion (change the anions ending to -ide) --- example NaCl = Sodium Chloride
  2. When naming compounds, do not change the suffix ---example: Sodium and Sulfate = Sodium Sulfate 3-4 only apply to polyatomic ions that contain oxygen
  3. When removing oxygens from polyatomic ions, ending changes from -ate to -ite to hypo-ite ---example: sulfate, sulfite, hyposulfite
  4. When adding oxygens to polyatomic ions, ending changes from -ate to per-ate ---example: chlorate, perchlorate
  5. The exceptions to rules 3 and 4 are ---C2O4 2- = oxalate ---C2H3O2 - = acetate ---OH- = hydroxide ---O2 2- = peroxide

CN- = cyanide NH4 + = ammonium H3O + = hydronium C2O4 2- = oxalate C2H3O2 - = acetate OH- = hydroxide O2 2- = peroxide Solute A substance that is dissolved in a solution. Solvent A liquid substance capable of dissolving other substances Photon A particle of electromagnetic radiation with no mass that carries a quantum of energy

Frequency formula speed of light/wavelength wavelength formula speed of light/frequency Energy Formula E = hv h= Planck's Constant v= frequency Planck's Constant 6.626 x 10^- Speed of Light 3.00 x 10^8 m/s