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DAT General Chemistry
Atomic Number - correct answer number of protons found in that atom; low number; (Z) Mass Number - correct answer Protons + Neutrons; high number; (A) Atomic Mass - correct answer relative mass of that atom compared to the mass of a carbon-12 atom (which is set at 12.00); measured in amu; 1 amu = - correct answer 1.66x10^- Atomic Weight - correct answer weight (g) of one mole (mol) of a given element (g/mol); the weighted average of all the masses (not the weights) of an element, weighted according to the natural abundance of the isotopic species of an element 1mol = ______ (Avagadro's Number) - correct answer 6.022x10^23 molecules Isotope - correct answer multiple species of an atom with same number of protons and a different number of neutrons (different mass numbers); generally exhibit same chemical properties Ernest Rutherford - correct answer 1911; gave experimental evidence that an atom has a dense, positively charged nucleus that accounts for a small portion of the volume of the atom Max Planck - correct answer developed first quantum theory; 1900; proposed that energy emitted as electromagnetic radiation from matter comes in discrete bundles called quanta; E=hv (h-Planck's constant) Planck's constant - correct answer 6.626x10^-34 J*s
The Bohr Model of the Atom - correct answer developed 1913 model of H atom using Rutherford and Planck's findings; H atom has central proton, electron travels around it in a circular orbit; centripetal force acting on the electron as it revolved around the nucleus was the electrical force between the positively charged proton and negatively charged electron; quantized angular momentum so it changed in discrete amounts in relation to the quantum number (L=nh/2pi) n=quantum number h=Planck's constant; from this Energy of an electron: E=-Rh/n^2, Rh=Rydberg constant 2.18*10^-18 J/electron Rydberg Constant - correct answer 2.18 x 10^-18 J/electron Smaller orbit of electron the... - correct answer lower the energy state What is the Bohr Model used for? - correct answer used to explain the atomic emission spectrum and atomic absorption spectrum of hydrogen; because these spectrum are not the continuous spectrum that classical physics would expect, they are line spectrum Balmer Series - correct answer 4 spectral lines that appear in the visible light region when a hydrogen atom undergoes a transition from energy levels n>2 to n=2. Lyman Series - correct answer Set of spectral lines appearing in the UV region when a hydrogen atom undergoes a transition from energy levels n>1 to n=1. Heisenberg Uncertainty Principle - correct answer impossible to determine the momentum and position of an electron simultaneously; means if the momentum of an electron is being measured accurately, its position will change and vice-versa Pauli exclusion principle - correct answer no 2 electrons in any given atom can possess the same set of four quantum numbers (n, l, ml, ms) Energy state of an electron - correct answer the position and energy of an electron described by its 4 quantum numbers (n, l, ml, ms)
Which are the valence electrons for groups IIIA through VIIIA (remaining column on right, excluding weird middle metals)? - correct answer the outermost s and p electrons Which are the valence electrons for the transition elements? - correct answer the outermost s electrons and the second to outermost d shell Dmitri Mendeleev - correct answer published first version of periodic table; showed elements ordered by atomic weight, produced patter of similar properties Henry Moseley - correct answer revised Mendeleev's periodic table; ordered elements based on atomic number; using this table the properties of elements that had not been discovered yet were predicted Periodic Law - correct answer chemical properties of the elements are dependent in a systematic way upon their atomic number Period - correct answer rows Groups - correct answer columns Atomic Radius - correct answer half the distance between the centers of 2 atoms of that element that are just touching each other; Atomic Radius decreases as you go from left to right across the periodic table and and increases as you go down Ionization Energy - correct answer energy required to remove an electron completely from a gaseous atom or ion; Ionization energy increases (gets harder) as you go from left to right and as you travel up Electron Affinity - correct answer energy change that occurs when an electron is added to a gaseous atom; how much an atom wants an electron; positive electron affinity represents energy released when an electron is added to an atom Electronegativity - correct answer measure of the attraction an atom has for electrons in a chemical bond (kinda the same thing as electron affinity); Pauling
electronegativity scale is most common electronegativity scale (ranges from 0.7 to 4.0); electronegativity increases from left to right and as you go up Ductility - correct answer ability to be drawn into wires (metals have it) To be an ionic bond the electronegativity difference must be greater than... - correct answer 1.7 on the Pauling Electronegativity scale Formal Charge - correct answer =(Valence e- in free atom) - 1/2Bonding - Nonbonding What is the electronegativity range for a polar covalent bond? - correct answer 0.4 -
Coordinate Covalent Bond - correct answer shared electron pair comes from the lone pair of one of the atoms in the molecule; once the bond forms it is indistinguishable form any other covalent bond Lewis Base - correct answer compound that can donate an electron pair to form a covalent bond Lewis Acid - correct answer A compound that can accept an electron pair to form a covalent bond Compound - correct answer a pure substance that is composed of 2+ elements in a fixed proportion; smallest unit is a molecule Molecule - correct answer combination of 2 or more atoms held together by covalent bonds; is the smallest unit of a compound displaying the properties of that compound Formula Weight - correct answer used for ionic compounds because you can't use "molecular weight"; is the sum of atomic weights according to the empirical formula of the substance
Isolated System - correct answer can not exchange energy or matter with surroundings; ex) insulated bomb reactor Closed system - correct answer can exchange energy but not matter with surroundings Open system - correct answer can exchange energy and matter with surroundings Isothermal Process - correct answer occurs when temperature of a system remains constant Adiabatic Process - correct answer occurs when no heat exchange occurs Isobaric Process - correct answer pressure of system remains constant Difference between heat and temperature - correct answer Heat= specific form of energy that can leave or enter a system; Temperature = average kinetic energy of particles Formula to calculate heat; q= - correct answer q=mcΔT; m=mass, c=specific heat, ΔT= change in temp State Functions - correct answer properties whose magnitude depends only on the initial and final states of the system (independent of path); ex) pressure, temperature, volume, enthalpy (H), entropy (S), free energy (G), internal energy (E or U) Standard State - correct answer a substance in its most stable form under standard conditions Standard Heat of Reaction (ΔH°rxn) - correct answer (ΔH°rxn) = (sum of ΔH°f products) - (sum of ΔH°f reactants); also (ΔH°rxn) = (ΔH bonds broken) - (ΔH bonds formed)
Hess's Law - correct answer states that enthalpies of reactions are additive (you can add up heats of reaction) because enthalpy is a state function; remember when adding, if you multiply reaction, multiply the enthalpy, and if you revers the reaction, reverse the sign on the enthalpy Breaking a Bond is endothermic or exothermic - correct answer endothermic ΔG = - correct answer ΔG = ΔH - TΔS ΔG° = -R T lnKeq; ΔG = ΔG°+ RT lnQ; R=8.314J/Kmol 1 atm = ____ mmHg = _____ torr - correct answer 1atm = 760mmHg = 760 torr Standard Temperature and Pressure (STP) - correct answer 273.15K, 1atm; note: different from standard conditions Boyle's Law - correct answer At a constant temperature, volume is inverse to pressure; P1V1 =P2V2; (combined (P1V1)/T1 = (P2V2)/T2 ) Charles' Law - correct answer Temperature and volume proportional at constant pressure; V1/T1 = V2/T2; (combined (P1V1)/T1 = (P2V2)/T2 ) Avagadro's Principle - correct answer At constant temperature and pressure, volume of gas is directly proportional to the number of moles of gas present; N1/V =N2/V2; At a constant temperature and pressure any gas with a given volume will have the same number of moles as another gas at that volume Ideal Gas Law - correct answer PV=nRT (R= 8.314 J/molK) How do you use the ideal gas law to calculate density? - correct answer replace n with n=(mass in grams)/(Molar Mass); PV=(m/MM)RT; therefore d=m/v=P(MM)/RT At moderately high pressures, a gases' volume is ____ than the ideal gas law would predict because... - correct answer less because of intermolecular interactions
Amorphous Solid - correct answer ex)glass; has no ordered 3D arrangement but the molecules are fixed in place; melts over a larger range of temperature than pure crystals because of the less ordered molecular distribution Ionic Solids - correct answer a kind of crystalline solid; aggregates of positively and negatively charged ions; no discrete ions; high melting points, high boiling points, poor electrical conductivity in the solid phase (due to strong electrostatic interactions which also cause ions to be relatively immobile) Metallic Solids - correct answer made of metal atoms packed together as closely as possible; have high melting and boiling points because of their strong covalent interactions; pure metallic structures (made of a single element) are described as layers of spheres of roughly the same radii Unit Cells - correct answer repeating units of crystals (both in ionic and metallic solids) are represented by unit cells; can have different shapes like simple cubic, body centered cubic and face centered cubic Evaporation - correct answer aka vaporization; liquid to gas; cooling process Condensation - correct answer gas to liquid Vapor Pressure - correct answer When condensation and evaporation are at equilibrium, the pressure the gas exerts over the liquid; vapor pressure increases as temperature increases because more molecules escape into the gas phase Boiling point - correct answer temperature at which vapor pressure of liquid equals external pressure Fusion/Melting - correct answer solid to liquid Solidification/ Crystallization/ Freezing - correct answer liquid to solid Sublimation - correct answer solid to gas
Deposition - correct answer gas to solid Phase diagram - critical point - correct answer Point where liquid and gas are no longer distinguishable Phase Diagram - triple point - correct answer unique for each substance, point where all three phases are in equilibrium Colligative Properties - correct answer physical properties derived solely from the number of particles present, not the nature of those particles, these properties usually associated with dilute solutions; ex) Freezing point depression and boiling point elevation Freezing Point Depression - correct answer For every mole of solute you add to water it decreases the freezing point by 1.86 °C, because the solute particles interfere with the crystal formation; therefore the kf (proportionality constant of water) = 1.86; Freezing pt depression = KfM, where M=molarity Boiling Point Elevation - correct answer liquid boils when its vapor pressure equals the atmospheric pressure; if the vapor pressure of a solution is lower than that of a pure solvent, more energy ( a higher temperature) will be needed for it to boil; Boiling point elevation=kbM; kb=proportionality constant, M= molarity Osmotic Pressure (II) in relation to concentration - correct answer osmotic pressure increases as the concentration of a solution increases; II=MRT; M=molarity, R=ideal gas constant 8.314 J/molK; T=temperature K Raoult's Law - correct answer When a solute is added to a solvent, it lowers the vapor pressure; Pa = xa * P°a; ΔP=P°a - Pa; where P°a= original pressure just above solvent, Pa= vapor pressure above solvent with solute; ΔP=xb * P°a; where xb= mole fraction of solute B in solvent A Solution - correct answer homogeneous mixture of substances that combine to form a single phase (usually liquid)
-ic - correct answer ion with a greater charge Ending for monatomic anions - correct answer -ide ex) hydride H- -ite - correct answer oxyanion with less oxygen -ate - correct answer oxyanion with more oxygen hypo- - correct answer element forms 4 oxyanions, less than -ite per- - correct answer element forms 4 oxyanions, more than -ate Electrolytes - correct answer solutes whose solutions are conductive Strong Electrolyte - correct answer a solute that completely dissociates into constituent ions Weak Electrolyte - correct answer a solute that does not completely dissociate in solution ex) acetic acid Nonelectrolytes - correct answer do not ionize at all when put in solution; retain their molecular structure, usually limits their solubility Molality (m) - correct answer mol of solute / kg solvent Normality (N) - correct answer number of gram equivalent weights of solute per liter solution Common Ion Effect - correct answer solubility of a salt is reduced when it is dissolved into a solution that already contains one of its ions, rather than pure solvent
Arrhenius Acid - correct answer species that produces H+ (a proton) in aqueous solution; **Failure of Arrhenius definition- does not describe acids outside of aq solution Arrhenius Base - correct answer Species that produces OH- (hydroxide ion) in aqueous solution; **Failure of Arrhenius definition- does not describe acids outside of aq solution Bronsted-Lowry Acid - correct answer species that donates protons Bronsted-Lowry Base - correct answer Species that accepts protons Lewis Acid - correct answer electron-pair acceptor Lewis Base - correct answer electron-pair donor Nomenclature of an acid - correct answer prefix=hydro, suffic= ic; ex) bromide goes to hydrobromic acid -ite oxyanion goes to oxyacid - correct answer acid ends in -ous; ex) hypochlorite goes to hypocholorous acid -ate oxyanion goes to oxyacid - correct answer acid ends in -ic; ex) perchlorate goes to percholoric acid Amphoteric/ Amphiprotic - correct answer can be either an acid or a base - can either gain or lose a proton Henderson-Hasselbalch - correct answer pH=pKa + log [conj. base]/[conj.acid]; estimates the pH of a solution in its buffer region Galvanic Cells always flow - correct answer anode to cathode
Binding Energy - correct answer amount of energy required to break up a given nucleus into protons and neutrons; that energy is converted to mass via Einstein's E=mc^2 so yields larger mass for protons and neutrons than that of the original nucleus (mass defect Mass Defect - correct answer difference in mass between original protons and neutrons and final protons and neutrons after they are broken up How to calculate binding energy - correct answer 1) find mass defect 2) Binding energy=mc^2, so BE=(mass defect)(932MeV/amu) Fusion - correct answer combining smaller nuclei into larger nucleus; sun uses fusion to power itself - sun fuses 4 hydrogen nuclei to make 1 helium nucleus which causes a release of energy Fission - correct answer split larger nucleus into smaller nuclei; fission can be induced by the absorption of a low energy neutron in certain nuclei; the fission reactions that power commercial nuclear electric - generating plants are the ones that release more neutrons that cause other atoms to undergo fission Nucleon/ baryon number conservation - correct answer states total # of neutrons + protons must stay the same - even if neutrons are converted into protons and vice versa, so total mass number (A) remains unchanged Radioactive Decay - correct answer naturally occurring spontaneous decay of certain nuclei accompanied by emission of specific particles; could be thought of as a type of fission Alpha Decay - correct answer emission of an alpha particle (which is a He with 2 protons, 2 neutrons); lose two protons and two neutrons; so Zdaughter = Zparent - 2; Adaughter=Aparent - 4 Alpha Particle - correct answer is a He nucleus with 2 protons and 2 neutrons; massive comparted to a beta particle and doubly charged; interacts with matter easily, therfore they do not penetrate shielding very far (ex lead sheets)
Beta (-) Decay - correct answer emission of a beta (-) particle (which is an electron); B- emitted by nucleus when a neutron in nucleus decays into a proton and a B- (electron, antineutrino); Zdaughter = Zparent +1, Adaughter = Aparent Beta (+) Decay - correct answer emission of a beta (+) particle (a anti-electron or positron); happens when a proton is split into a positron and a neutron; Zdaughter = Zparent - 1; Adaughter = Aparent Gamma Decay - correct answer emission of a gamma particle (high energy photons, no charge); just lowers the energy of parent nucleus without changing Z or A Electron Capture - correct answer some unstable radionuclides (generic term for any radioactive isotope) can capture an inner (K or L shell) electron that can combine with a proton to form a neutron; (inverse of B- decay); Adaughter= Aparent; Zdaughter= Zparent - 1 How do you calculate fraction remaining after x half lives? - correct answer (1/2)^x Exponential Decay formula - correct answer n=n°e^(ln2t/half-life) which is n=n°e^(0.693t/half-life)
