ACS EXAM REVIEW QUESTIONS WITH CORRECT ANSWERS., Exams of Chemistry

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ACS EXAM REVIEW QUESTIONS WITH CORRECT

ANSWERS

Rutherford's Gold Foil Experiment - CORRECT ANSWER-✔✔✅proposed that atoms consist of a tiny, massive, positive nucleus surrounded by electrons nucleus - CORRECT ANSWER-✔✔✅contains all the positive charge and nearly all the mass of the atom James Chadwick - CORRECT ANSWER-✔✔✅discovered the neutron cathode rays - CORRECT ANSWER-✔✔✅move from negative electrode to positive electrode (like electrons in a voltaic cell) Thompson's Cathode Ray Experiment - CORRECT ANSWER-✔✔✅discovery of the electron (also the discovery that atoms are divisible into smaller particles) Millikin's oil drop experiment - CORRECT ANSWER-✔✔✅determined the charge of the electron through highest grade clock oil and electrons from X-ray that clung to positive charged oil drops- determined that electrons are some whole value of charge (Faraday constant) Thompson's plum pudding model - CORRECT ANSWER-✔✔✅model of a spherical atom composed of diffuse positively charged matter in which electrons are embedded like raisins in plum pudding atomic number - CORRECT ANSWER-✔✔✅number of protons (Z) mass number - CORRECT ANSWER-✔✔✅number of protons and neutrons (nucleons) (A) isotopes - CORRECT ANSWER-✔✔✅same element with different numbers of neutrons

mass spectrometry - CORRECT ANSWER-✔✔✅a method for measuring the relative masses and abundances of atomic scale particles very precisely empirical formula - CORRECT ANSWER-✔✔✅shows relative number of atoms in a compound molecular formula - CORRECT ANSWER-✔✔✅shows the actual number of atoms of each element in a molecule of compound aufbau principle - CORRECT ANSWER-✔✔✅the rule that electrons occupy the orbitals of lowest energy first quantum mechanics - CORRECT ANSWER-✔✔✅mechanics applied to the atomic and nuclear level and dealing with photons and other quanta that show both wave and particle behavior Heisenburg's uncertainty principle - CORRECT ANSWER-✔✔✅the statement that, due to the laws of quantum mechanics, it is impossible to simultaneously exactly measure a particle's position and momentum or to exactly measure a particle's energy for a finite amount of time. electron energy - CORRECT ANSWER-✔✔✅The strength of attachment of an electron to the nucleus of an atom; the closer and electron to the nucleus, the higher the electron binding energy. quantum numbers - CORRECT ANSWER-✔✔✅the four numbers that define each particular electron of an atom. The Principle Quantum Number (n) describes the electrons' energy and distance from the nucleus. The Angular Momentum Quantum Number (l) describes the shape of the orbital in which the electron resides. The Magnetic Quantum Number (m) describes the orientation of the orbital in space. The Spin Quantum Number (s) describes whether the spin of the electron is positive or negative. photon - CORRECT ANSWER-✔✔✅packet of energy electromagnetic radiation - CORRECT ANSWER-✔✔✅A form of energy exhibiting wavelike behavior as it travels through space; can be described by wavelength, frequency, amplitude, and speed.

radial probability distributions - CORRECT ANSWER-✔✔✅a graph in which the total probability of finding the electron in each spherical shell is plotted versus the distance from the nucleus isoelectronic - CORRECT ANSWER-✔✔✅same number of electrons alpha particle - CORRECT ANSWER-✔✔✅... beta particle - CORRECT ANSWER-✔✔✅... gamma ray - CORRECT ANSWER-✔✔✅... group 1 - CORRECT ANSWER-✔✔✅alkali metals group 2 - CORRECT ANSWER-✔✔✅alkaline earth metals group 7 - CORRECT ANSWER-✔✔✅halogens group 8 - CORRECT ANSWER-✔✔✅noble gases electromagnetic spectrum (decreasing energy) - CORRECT ANSWER-✔✔✅x-ray, uv-ray, visible light, infrared light, microwaves, tv, radio waves higher photon energy - CORRECT ANSWER-✔✔✅higher frequencies (∨) and shorter wavelengths (λ) speed of light (c) - CORRECT ANSWER-✔✔✅3.00 x 10⁸ ms⁻¹, maximum speed of any and all motion; electromagnetic waves travel at this speed principal quantum number (n) - CORRECT ANSWER-✔✔✅a positive integer (1,2,3,etc.) that indicates the relative size of the orbital and therefore the relative distance from the nucleus of the peak in the radial probability distribution plot. The higher the n value, the higher the energy level.

angular momentum quantum number (l) - CORRECT ANSWER-✔✔✅an integer from 0 to n-1. It is related to the shape of the orbital. (notice that n limits l) (the possible number of l values equals the number of n) quantum number (ml) - CORRECT ANSWER-✔✔✅an integer from -l through 0 to +l. It prescribes the orientation of the orbital in the space around the nucleus. (number of possible ml= 2l+1) quantum number (ms) - CORRECT ANSWER-✔✔✅direction of spin (+1/2 or -1/2) hund's rule - CORRECT ANSWER-✔✔✅electrons in orbitals of the same energy do not pair until they have to atomic line spectra - CORRECT ANSWER-✔✔✅(further explanation) provide evidence that the energy state of an electron in an atom is quantized absorbed - CORRECT ANSWER-✔✔✅energy must be ______ for an electron to move from one energy state in an atom to another energy state that is more remote from the nucleus emitted - CORRECT ANSWER-✔✔✅energy must be _____ for an electron to move from one energy state in an atom to another energy state that is closer to the nucleus paramagnetism - CORRECT ANSWER-✔✔✅exhibited by a species with unpaired electrons diamagnetism - CORRECT ANSWER-✔✔✅exhibited by a species with all electrons paired allotrope - CORRECT ANSWER-✔✔✅a structurally different form of an element; graphite and a diamond have the same formula but different structure to the atoms isomer - CORRECT ANSWER-✔✔✅compounds that have the same simple formula but different three- dimensional structures

polymer - CORRECT ANSWER-✔✔✅large compound formed from combinations of many monomers s sublevel - CORRECT ANSWER-✔✔✅l=0 (spherical) p sublevel - CORRECT ANSWER-✔✔✅l=1 (dumbbell shape) d sublevel - CORRECT ANSWER-✔✔✅l=2 (clover shape/dumbbell and do-nut) f sublevel - CORRECT ANSWER-✔✔✅l= diffraction by crystals - CORRECT ANSWER-✔✔✅... Valence Electron Pair Repulsion (VSPER) Theory - CORRECT ANSWER-✔✔✅each group of valence electrons around a central atom is located as far away as possible from others in order to minimize repulsion dipole moment - CORRECT ANSWER-✔✔✅... Valence bond theory - CORRECT ANSWER-✔✔✅... hybrid orbitals - CORRECT ANSWER-✔✔✅... molecular orbital theory - CORRECT ANSWER-✔✔✅... ionization energy - CORRECT ANSWER-✔✔✅energy required for the complete removal of 1 mol of electrons from 1 mol of gaseous atoms or ions (increases across a period, decreases down a group)

electron affinity - CORRECT ANSWER-✔✔✅energy change accompanying the addition of 1 mole of electrons to 1 mol of gaseous atoms or ions (EA₁ is usually negative: releases energy, EA₂ is always positive: requires energy to overcome electrostatic repulsions) high energy photons - CORRECT ANSWER-✔✔✅have enough energy to disrupt covalent bonds low ionization energy - CORRECT ANSWER-✔✔✅readily lose electrons to form positive ions high electron affinity - CORRECT ANSWER-✔✔✅readily gain electrons to form negative ions ionic bonds - CORRECT ANSWER-✔✔✅result when atoms exchange electrons covalent bonds - CORRECT ANSWER-✔✔✅result when atoms each contribute an electron to a shared pair coordinate covalent bonds - CORRECT ANSWER-✔✔✅result when one atom contributes two of its electrons to a shared pair metallic bonds - CORRECT ANSWER-✔✔✅result when atoms free one or more valence electrons to the metal lattice properties of ionic compounds - CORRECT ANSWER-✔✔✅hard, high melting; conduct a current only when melted or dissolved; strong intermolecular attractions properties of covalent compounds - CORRECT ANSWER-✔✔✅low melting and boiling points; weak intermolecular attractions properties of metallic compounds - CORRECT ANSWER-✔✔✅metallic behavior correlates with large atomic size and low ionization energy (increases down a group and decreases across a period)

properties of covalent network solid compounds - CORRECT ANSWER-✔✔✅very hard and big melting; covalent bonds throughout the substance (diamond=hardest known natural substance) electronegativity - CORRECT ANSWER-✔✔✅relative ability of a bonded atoms to attract the shared electrons electromagnetic radiation - CORRECT ANSWER-✔✔✅consists of energy propagated by electric and magnetic fields that alternately increase and decrease in intensity as they move through space frequency - CORRECT ANSWER-✔✔✅(∨) number of cycles the wave undergoes per second and is expressed in hertz (units of s⁻¹) wavelength - CORRECT ANSWER-✔✔✅(λ) distance between any point on a wave and the corresponding point on the proximate wave; distance wave travels during one cycle; (measured in meters. but also expressed in pico (10⁻⁹) and femto (10⁻¹²) meters and Angstroms (10⁻¹⁰) amplitude - CORRECT ANSWER-✔✔✅height of the crest for each wave; related to the intensity of the wave c = ∨ x λ - CORRECT ANSWER-✔✔✅formula for speed of wave electromagnetic spectrum - CORRECT ANSWER-✔✔✅all waves in the _____ travel at the same speed but differ in frequency and wavelength gamma ray, x-ray, uv-ray, visibile, infrared, microwave, radio - CORRECT ANSWER-✔✔✅electromagnetic waves in order of decreasing frequency refraction - CORRECT ANSWER-✔✔✅the phenomenon that describes when light passes from one medium into another, its speed changes (the wave will continue at a different angle) diffraction - CORRECT ANSWER-✔✔✅the phenomenon that describes when a wave strikes the edge of an object, it will bend around it

interference - CORRECT ANSWER-✔✔✅if waves of light pass through adjacent slits, the emerging circular waves interact with each other constructive interference - CORRECT ANSWER-✔✔✅when crests of waves coincide in phase and the amplitudes add together destructive interference - CORRECT ANSWER-✔✔✅when the crests of one wave coincides with the troughs of another wave and the amplitudes cancel blackbody radiation - CORRECT ANSWER-✔✔✅light given off by a hot blackbody that led to Max Plank's quantization of energy in his equation E= nhv (later it followed that if an atom can only emit certain quantities of energy, then an atom can only have certain quantities of energy- photons) 6.626x10⁻³⁴ - CORRECT ANSWER-✔✔✅Plank's constant quantum - CORRECT ANSWER-✔✔✅defined amount of energy (energy packet) photoelectric effect - CORRECT ANSWER-✔✔✅the flow of current when monochromatic light shines of sufficient frequency (minimum value/threshold) shines on a metal plate photons - CORRECT ANSWER-✔✔✅(acc. to Einstein) light is quantized into small bundles of electromagnetic energy called ______. (also called quanta) atomic line spectrum - CORRECT ANSWER-✔✔✅a series of fine lines of individual colors separated by colorless (black) spaces (each species has a characteristic spectrum) 1/λ=R (1/n₁²-1/n₂²) - CORRECT ANSWER-✔✔✅Rydberg equation (R=1.0968x10⁷ m⁻¹) Bohr model of the hydrogen atom - CORRECT ANSWER-✔✔✅1. H atom has only certain allowable energy states (stationary states)

2. atom does not radiate energy while in one of its stationary states (atom does not change energy while the electron moves within an orbit)
3. the atom changes to another stationary state only by absorbing or emitting a photon whose energy equals the difference in energy between the two states H He⁺ - CORRECT ANSWER-✔✔✅bohr model is only successful in explaining the electron behavior of ____ and ____, which have only one electron -2.18x10⁻¹⁸(1/n²final- 1/n²initial) - CORRECT ANSWER-✔✔✅∆E (for energy levels)= (more negative= more energy= electron is further from the nucleus) de Broglie wavelength - CORRECT ANSWER-✔✔✅matter behaves as though it moves in a wave (an object's wavelength is inversely proportional to its mass) electron density diagram - CORRECT ANSWER-✔✔✅(radial probability distribution plot) probable distribution of electrons around an atom in an electron cloud shown through Schrodinger's model Pauli Exclusion principle - CORRECT ANSWER-✔✔✅no two electrons in the same atom can have the same four quantum numbers Coulomb's Law - CORRECT ANSWER-✔✔✅electric force between charged objects depends on the distance between the objects and the magnitude of the charges. electrons penetrate - CORRECT ANSWER-✔✔✅the lower an l value the more ____ s<p<d<f - CORRECT ANSWER-✔✔✅order of sub level energies decreases; increases - CORRECT ANSWER-✔✔✅atomic radius ______ from left to right and ______ from top to bottom

large jump in ionization energy (IE) - CORRECT ANSWER-✔✔✅after the outer valence electrons have been removed, there is a _______ smaller - CORRECT ANSWER-✔✔✅cations are ___ than their parent atoms larger - CORRECT ANSWER-✔✔✅anions are ____ than their parent atoms bonding - CORRECT ANSWER-✔✔✅_____ lowers the potential energy between positive and negative particles ionic bonding - CORRECT ANSWER-✔✔✅electron transfer that occurs between atoms with large differences in their tendencies to lose or gain electrons covalent bonding - CORRECT ANSWER-✔✔✅electron sharing that occurs between atoms with little differences in their tendencies to lose or gain electrons; electron sharing between pairs of atoms leads to strong localized bonds within individual molecules; weak intermolecular forces, strong intramolecular forces metallic bonding - CORRECT ANSWER-✔✔✅occurs when metal atoms in a sample pool their valence elections into an evenly distributed "sea" of electrons that "flows" between and around the metal ion cores delocalized - CORRECT ANSWER-✔✔✅delocalized electrons= ____ bonding lattice energy - CORRECT ANSWER-✔✔✅(∆H°lattice) the enthalpy change that occurs when 1 mol of ionic solid separates into gaseous ions greater; higher - CORRECT ANSWER-✔✔✅cations and anions with smaller atomic radii have ____ lattice energy; cations and anions with _____ charges have more lattice energy covalent bond - CORRECT ANSWER-✔✔✅arises from the balance between nucleus-electron attractions and electron-electon and nucleus-nucleus repulsions

bond order - CORRECT ANSWER-✔✔✅number of electron pairs being shared by a pair of bonded atoms bond energy - CORRECT ANSWER-✔✔✅energy required to overcome covalent bonds bond length - CORRECT ANSWER-✔✔✅the distance between the nuclei of two bonded atoms ∆Hrxn= - CORRECT ANSWER-✔✔✅∑∆Hreactant bonds broken + ∑∆Hproduct bonds formed ∆Hrxn= - CORRECT ANSWER-✔✔✅∑BEreactants-∑BEproducts surface tension - CORRECT ANSWER-✔✔✅... larger - CORRECT ANSWER-✔✔✅substances with low molecular mass and/or little interaction among particles will yield a ______ vapor pressure Graham's Law of Effusion - CORRECT ANSWER-✔✔✅... directly - CORRECT ANSWER-✔✔✅kinetic energy of gas particles is _____ proportional to temperature velocity of gas molecules - CORRECT ANSWER-✔✔✅(square root formula) heat of melting - CORRECT ANSWER-✔✔✅the heat energy absorbed by a substance as it transforms from solid to liquid (cooling curve shows changes in heat, not melting points/temps of melting) specific heat - CORRECT ANSWER-✔✔✅the heat required to raise the temperature of one gram of a substance one degree centigrade melting point - CORRECT ANSWER-✔✔✅the temperature at which a substance changes from a solid to a liquid

critical temperature - CORRECT ANSWER-✔✔✅... molality - CORRECT ANSWER-✔✔✅... Henry's law - CORRECT ANSWER-✔✔✅the solubility of a gas is directly proportional to its pressure vapor pressure lowering - CORRECT ANSWER-✔✔✅∆P= Xsolvent x P°solvent boiling point elevation - CORRECT ANSWER-✔✔✅∆Tb=Kbm freezing point depression - CORRECT ANSWER-✔✔✅∆Tf=Kfm osmotic pressure - CORRECT ANSWER-✔✔✅π=MRT colligative properties - CORRECT ANSWER-✔✔✅properties that depend on number, not on chemical nature: vapor pressure lowering, boiling point elevation, freezing point depression, osmotic pressure saturated - CORRECT ANSWER-✔✔✅maximum amount of dissolved solute at a given temperature in the presence of undissolved solute unsaturated - CORRECT ANSWER-✔✔✅add more solute and more will dissolve until the solution becomes saturated supersaturated - CORRECT ANSWER-✔✔✅unstable relative to the saturated solution; if you add a "seed" crystal or solute, or just tap the container, the excess solute crystallizes immediately, leaving a saturated solution Henry's law - CORRECT ANSWER-✔✔✅the solubility of a gas (Sgas) is directly proportional to the partial pressure of the gas (Pgas) above the solution (Sgas= Kh x Pgas)

Molality (m) - CORRECT ANSWER-✔✔✅amount (mol) of solute/ mass (kg) of solvent mass percent - CORRECT ANSWER-✔✔✅[mass of solute/ (mass of solute + mass of solvent)] x100% volume percent - CORRECT ANSWER-✔✔✅(volume of solute/ volume of solution) x 100% mole fraction - CORRECT ANSWER-✔✔✅amount (mol) of solute/ [amount (mol) of solute + amount (mol) of solvent] mole percent - CORRECT ANSWER-✔✔✅mole fraction x 100% simple cubic structure - CORRECT ANSWER-✔✔✅coordination number= 6 (1 atom/cell) 52% packing efficiency body centered cubic structure - CORRECT ANSWER-✔✔✅coordination number=8 (2 atoms/cell) 68% packing efficiency face centered cubic structure - CORRECT ANSWER-✔✔✅coordination number = 12 (4 atoms/cell) 74% packing efficiency coordination number - CORRECT ANSWER-✔✔✅number of nearest neighbors surrounding an atom abab - CORRECT ANSWER-✔✔✅hexagonal closest packing placement abcabc - CORRECT ANSWER-✔✔✅cubic closest packing placement cubic closest and hexagonal closest packing - CORRECT ANSWER-✔✔✅most efficient forms of packing that most metallic elements crystallize in

C= q/ (m x ∆T) - CORRECT ANSWER-✔✔✅specific heat formula (g) qsystem= -qwater - CORRECT ANSWER-✔✔✅calorimeter heat of water and heat of system entropy - CORRECT ANSWER-✔✔✅thermodynamic quantity that expresses the disorder or randomness in a system ∆G= ∆H - T∆S - CORRECT ANSWER-✔✔✅Gibbs free energy formula equilibrium - CORRECT ANSWER-✔✔✅when water is boiling, there is an ______ between the rate at which the molecules are escaping the surface and the rate at which they are condensing 0 - CORRECT ANSWER-✔✔✅∆G at equilibrium constant volume - CORRECT ANSWER-✔✔✅in a bomb calorimeter, reactions are carried out at ________ endothermic - CORRECT ANSWER-✔✔✅if the solution of a calorimeter gets cold the reaction is ______ exothermic - CORRECT ANSWER-✔✔✅if the solution of a calorimeter gets warm the reaction is _______ Gibbs energy - CORRECT ANSWER-✔✔✅measure of thermodynamic driving force (it is a state function) reaction dynamics - CORRECT ANSWER-✔✔✅aka rate of reaction or reaction kinetics reaction mechanism - CORRECT ANSWER-✔✔✅steps of intermediate events of a reaction instantaneous rate or relationship between concentration and time - CORRECT ANSWER-✔✔✅basic experimental techniques for studying reaction dynamics involve determining the ________.

ln(k₂/k₁)=-Ea/R [(1/T₂)-(1/T₁)] - CORRECT ANSWER-✔✔✅Arrhenius equation (k=Ae (-Ea/RT)) ln([A]₀/[A])= kt - CORRECT ANSWER-✔✔✅first order reaction equation ... - CORRECT ANSWER-✔✔✅second order reaction equation ... - CORRECT ANSWER-✔✔✅zeroth order reaction equation ... - CORRECT ANSWER-✔✔✅Arrhenius constant ... - CORRECT ANSWER-✔✔✅activation energy k= .693/t.₅ - CORRECT ANSWER-✔✔✅half life equation concentrations of reactants and products - CORRECT ANSWER-✔✔✅____ has no effect on the rate constant dynamic equilibrium - CORRECT ANSWER-✔✔✅occurs even though the macroscopic view indicates constant, but seldom equal concentrations for each substance