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Answers 2023
John Dalton - Correct Answer ✅ Proposed that matter is composed of atoms; these atoms have different identities called elements, which combine to form compounds; measured masses of reactants and products. J.J. Thompson - Correct Answer ✅ Observed deflection of particles in a cathode ray tube; proposed that atoms are composed of positive and negative charges; developed the plum pudding model of the atom Robert Millikan - Correct Answer ✅ Calculated the charge-to-mass ratio of electrons using oil drops falling in an electric field; surmised the charge of a single electron Ernest Rutherford - Correct Answer ✅ Used the deflection of alpha particles in a cathode ray tube to discover that most of the atom is empty space, with protons and neutrons centered in the nucleus. Niels Bohr - Correct Answer ✅ Determined that electrons exist around the nucleus at a fixed radius; electrons with higher energy exist farther from the nucleus. Electrons give off electromagnetic radiation when moving between energy levels. Max Planck - Correct Answer ✅ Determined that energy is quantized, or composed of discrete bundles.
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6.63 x 10^-34 J*sec - Correct Answer ✅ Planck's Constant (h) 3.00 x 10^8 m/sec - Correct Answer ✅ Speed of Light (c) E = hv - Correct Answer ✅ Energy of a Photon Formula (1) E = hc / wavelength - Correct Answer ✅ Energy of a Photon Formula (2) Louis DeBroglie - Correct Answer ✅ Combined Einstein's relationship between mass and energy and the relationship between velocity and the wavelength of light. All particles with momentum have a corresponding wave nature. Wavelength = h / mv - Correct Answer ✅ Wavelength of Particles Formula Heisenberg's Uncertainty Principle - Correct Answer ✅ It is impossible to simultaneously know the position and momentum of an electron. Erwin Schrodinger - Correct Answer ✅ Attributed a wave function to electrons, describing the probability of where an electron might exist.
Answers 2023
Pauli Exclusion Principle - Correct Answer ✅ No two electrons can occupy the exact same energy level or have the same set of four quantum numbers Quantum numbers - Correct Answer ✅ 1. Principal (n)
- Angular Momentum (l)
- Magnetic (ml)
- Magnetic Spin (ms) Principal Quantum Number - Correct Answer ✅ The shell or energy level an electron occupies; values from 1-7. Electrons with higher values are farther from the nucleus. Angular Momentum Quantum Number - Correct Answer ✅ The subshell the electron occupies; describes the shape of an electron's orbital. n = 1: l = 0 (s) n = 2: l = 0 (s), 1 (p) n = 3: l = 0 (s), 1 (p), 2 (d) n = 4: l = 0 (s), 1 (p), 2 (d), 3 (f) Magnetic Quantum Number - Correct Answer ✅ Represents the orbital position. l = 0: ml = 0 (1 possible s orbital)
Answers 2023
l = 1: ml = -1, 0, 1 (3 possible p orbitals) l = 2: ml = -2, -1, 0, 1, 2 (5 possible d orbitals) l = 3: ml = -3, -2, -1, 0, 1, 2, 3 (7 possible f orbitals) Magnetic Spin Quantum Number - Correct Answer ✅ Each orbital contains at most 2 electrons: one with a positive spin (+1/2) and one with a negative spin (-1/2) Dimagnetic - Correct Answer ✅ Elements that have paired electrons in each orbital; all subshells are filled. These elements aren't affected by magnetic fields Paramagnetic - Correct Answer ✅ Elements that have an unpaired electron in at least one orbital; creates a magnetic field in the atom that responds to external magnetic fields. Electron Configurations - Correct Answer ✅ Identify the number of electrons in each type of orbital at each energy level Orbital notation - Correct Answer ✅ Identifies where each electron exists in each orbital. Example: Nitrogen (N) = 1s^2:2s^2:2p^
Answers 2023
Nonmetals will readily form these bonds with other nonmetals in order to obtain stability. Valence electrons - Correct Answer ✅ The electrons in the outermost shell of an atom Sigma bond - Correct Answer ✅ The first covalent bond between nonmetals Pi bond - Correct Answer ✅ Each additional covalent bond between non-metals after a sigma bond; much weaker than sigma bonds. Nonpolar covalent bond - Correct Answer ✅ Created when atoms share their electrons equally; usually occurs when two atoms have similar or the same electron affinity. The closer the values of their electron affinity, the stronger the attraction; normally the difference in electronegativity is >0.4. Polar covalent bond - Correct Answer ✅ Occurs when the electrons between atoms are not equally shared. The atom with the higher electronegativity will have a stronger pull for electrons, resulting in the molecule having a slightly positive side and a slightly negative side. Normally the difference in electronegativity is between 0.4 and 1.7.
Answers 2023
Dipole moment - Correct Answer ✅ The measure of net molecular polarity. The larger the difference in electronegativities of bonded atoms, the larger the moment. Network covalent structure - Correct Answer ✅ A chemical structure in which the atoms are bonded by a group of covalent bonds in a continuous network. Lewis Structure - Correct Answer ✅ A model of the valence electrons that are involved in covalent bonding Resonance structure - Correct Answer ✅ An attempt to model delocalized electrons Hybridization - Correct Answer ✅ The process by which electrons mix traits of different atomic orbitals to create bonding orbitals; or, the concept of mixing atomic orbitals into new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds VSEPR - Correct Answer ✅ Valence shell electron-pair repulsion; electron pairs will repel each other, making each electron pair as far away as possible from every other electron pair.
Answers 2023
Positron decay - Correct Answer ✅ A nucleus emits a particle that degrades into a positron; converts a proton into a neutron and a positron. Gamma radiation - Correct Answer ✅ Given off in combination with alpha and beta decay; the rays given off are photons. Half-life - Correct Answer ✅ The time it takes for 50% of an isotope to decay. T = 0.693 / k - Correct Answer ✅ Half-life formula P1V1 = P2V (The volume of a gas is inversely proportional to its pressure, when temperature is constant) - Correct Answer ✅ Boyle's Law V1T2 = V2T (The volume of a gas is directly proportional to temperature, when pressure is constant) - Correct Answer ✅ Charles's Law P1T2 = P2T
Answers 2023
(The pressure of a gas is directly proportional to temperature, when volume is constant) - Correct Answer ✅ Law of Gay-Lussac Ptotal = P1 + P2 + ... + Pn (The total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the gases in the mixture.) - Correct Answer ✅ Dalton's Law V1n2 = V2n (The volume of a gas is proportional to the number of moles of gas present when temperature is constant) - Correct Answer ✅ Avogadro's Law PV = nRT (Pressure x Volume = number of gas moles x ideal gas constant x absolute temperature) - Correct Answer ✅ Ideal gas law formula 0.082 Latm / Kmol - Correct Answer ✅ Ideal gas constant (R) 273 K; 1.0 atm; 1.0 mol gas = 22.4 L gas - Correct Answer ✅ Standard Temperature and Pressure (3 components)
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Critical point - Correct Answer ✅ The temperature and pressure point on a phase diagram above which the substance must exist as a gas. Triple point - Correct Answer ✅ The temperature and pressure point on a phase diagram at which a substance may exist in all three phases Vapor pressure curve - Correct Answer ✅ Defines the boundary between the liquid & gas phases on a phase diagram Crystalline solids - Correct Answer ✅ Composed of structural units bounded by a specific geometric pattern. Example: table salt Unit cell - Correct Answer ✅ The smallest repeating unit in a crystalline solid Simple cubic unit cells - Correct Answer ✅ These have one atom at each of the corners of the cube; containing a total of one atom per unit cell. Face-centered crystal - Correct Answer ✅ A simple cubic unit cell with one additional atom shared between two unit cells on each face of the cube; a total of three atoms per unit cell.
Answers 2023
Body-centered crystal - Correct Answer ✅ A simple cubic unit cell with one additional atom in the center of the cube, for a total of two atoms per unit cell Amorphous solids - Correct Answer ✅ These don't display a specific geometry; example: glass Solvation - Correct Answer ✅ The interaction of solvent molecules with solute molecules to form loosely bonded combinations. Hydration - Correct Answer ✅ The solvation process when water is the solvent. Miscible solutions - Correct Answer ✅ These occur when one substance is soluble in all proportions with another substance. Saturation - Correct Answer ✅ A solid solute is in equilibrium with dissolved solute. Solubility - Correct Answer ✅ The molar concentration of dissolved solute at saturation
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(change in solvent boiling point = molal boiling point constant of solvent x molality of solute x van't hoff factor of solute) - Correct Answer ✅ Boiling point elevation; or, change in solvent boiling point ∆T = (kf)(m)(i) (change in solvent freezing point = molal freezing point constant of solvent x molality of solute x van't hoff factor of solute) - Correct Answer ✅ Freezing point depression; or, change in solvent freezing point πV = nRTi (osmotic pressure x volume of solution = moles of solute x ideal gas constant x temperature x Van't Hoff factor of solute) - Correct Answer ✅ Osmotic pressure formula Arrhenius Theory - Correct Answer ✅ Acids ionize in water to donate protons; bases ionize in water to produce hydroxide ions. Bronsted-Lowry Theory - Correct Answer ✅ Acids donate protons and bases accept protons; a proton moves from one compound to the other. Lewis theory - Correct Answer ✅ An acid is an electron-pair acceptor, and a base is an electron-pair donor.
Answers 2023
Neutralization - Correct Answer ✅ The process where an Arrhenius acid and base are combined to form a salt and water. Amphoteric - Correct Answer ✅ Compounds that can act as either acids or bases Precipitation reactions - Correct Answer ✅ Occur when soluble reactants are mixed together to form an insoluble product (see solubility rules) Net ionic reaction - Correct Answer ✅ A reaction that shows only ions that combine to form the precipitate. Spectator ions - Correct Answer ✅ Ions that remain dissolved in a precipitation reaction. Oxidation reaction - Correct Answer ✅ An atom increases control over an electron; a loss of electrons Reduction reaction - Correct Answer ✅ An atom decreases control over an electron; a gain of electrons
Answers 2023
E(cell) = E0 (cell) - RT / nF ln Q (Cell voltage under non-standard conditions = cell voltage under standard conditions - ideal gas constant x temperature / moles of electrons x Faraday's constant x natural log of the reaction quotient for reduction reaction) - Correct Answer ✅ Nernst Equation; used to calculate the cell voltage under non-standard conditions Electrolytic cells - Correct Answer ✅ Use electrons from a power source to force an otherwise non-spontaneous oxidation-reduction reaction to occur. 1.0 F = 1.0 mol electrons = 96,486 Coulombs - Correct Answer ✅ Faraday's Law (F) 96,486 C/mol - Correct Answer ✅ Faraday's Constant I = q / t (Current = charge / time) - Correct Answer ✅ Current formula (measured in amperes) Le Chatelier's Principle - Correct Answer ✅ Whena system at equilibrium is disturbed by a change in pressure, temperature, or concentration, the reaction will shift to minimize the change and establish a new equilibrium
Answers 2023
K(eq) = [C]c [D]d / [A]a [B]b - Correct Answer ✅ Equilibrium constant (Keq); aka law of mass action K(reverse) = 1 / K(forward) - Correct Answer ✅ Equilibrium constant for a reverse reaction Q= [C]c [D]d / [A]a [B]b - Correct Answer ✅ Reaction Quotient When Q > K, reaction proceeds left When Q < K, reaction proceeds right When Q = K, reaction is in equilibrium K(p) = K(c)(RT)^∆n (partial pressure equilibrium constant = molar concentration equilibrium constant x ideal gas law x absolute temperature x net moles of gas (products - reactants) - Correct Answer ✅ Gas Equilibrium Constant Buffer - Correct Answer ✅ An aqueous combination of a weak acid and its conjugate base, or a weak base and its conjugate acid pH = pK(a) + log ([A-] / [HA])
