CHEM 1211 FINAL EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026

CHEM 1211 FINAL EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 Rules for Significant Figures - Answers 1. leading zeros are NEVER significant 2. trapped zeros are ALWAYS significant 3. trailing zeros are significant only with a decimal point 4. exact numbers are always significant Rules for Naming Molecular Compounds - Answers 1. 1st word= element in lowest group 2. higher period goes first 3. 2nd word= root + -ide 4. Greek numeral prefixes indicate number of atoms Rules of Naming Ionic Compounds - Answers 1. 1st word= name of metallic element 2. nonmetallic element named with root + -ide 3. No Greek numeral prefixes used crystalline solid - Answers a solid made of an ordered array of atoms, ions, molecules hexagonal closest-packed (hcp) - Answers a crystal lattice in which the layers of atoms or ions have an ababab... stacking pattern unit cell - Answers the basic repeating unit of the arrangement of atoms, ions, or molecules in a crystalline solid hexagonal unit cell - Answers an array of 9 closest-packed particles that are the repeating unit in a hexagonal closest-packed crystal crystal structure - Answers an ordered arrangement in 3D space of the particles that make up a crystalline solid cubic closest-packed (ccp) - Answers a crystal structure composed of face-centered cubic unit ce;;s and layers of particles having an abcabc... stacking pattern face-centered cubic (fcc) unit cell - Answers an array of closest-packed particles that has eight particles at the corners and six at the centers of each face of the cube atoms in body - Answers completely located in unit cell= 1 atoms atoms in edges - Answers shared by 4 cels; 1/4 in each cell= (1/4 per edge) 12 edges= 3 atoms atoms on corners - Answers shared by 8 cells; 1/8 in each cell= (1/8 per corner) 8 corners= 1 atom atoms on faces - Answers shared by 2 cells; 1/2 in each cell= (1/2 per face) 6 faces= 3 atoms packing efficiency - Answers percentage of the total volume of a unit cell occupied by the spheres; (V spheres/ V unit cell) simple cubic (sc) unit cell - Answers a cell with atoms only at the eight corners of a cube body-centered cubic (bcc) unit cell - Answers a cell with atoms at the eight corners of a cube and at the center of the cell Unit Cell Dimensions - Answers Simple Cubic: atoms touch along cell edge, 1 equivalent atom/unit cell, r=L/2=.5L; BCC: atoms touch along body diagonal, 2 atoms/unit cell, r=(L√3)/4=.433L; FCC: atoms touch along face diagonal, 4 atoms/unit cell, r=(L√2)/4=.3536L alloy - Answers blend of host metal and one or more other elements, which may or may not be metals, that are added to change the properties of the host metal substitutional alloy - Answers atoms of the nonhost element replace host atoms in the crystal lattice; similar structure, comparable atomic radius interstitial alloy - Answers nonhost atoms occupy spaces between atoms of host; significant difference in atomic radius ionic solids - Answers positive and negative ions held together by electrostatic attractions; high melting points, brittle, poor conductors when solid molecular solids - Answers atoms/molecules held together by London dispersion forces, dipole-dipole, or H bonds; low melting points, flexibility, poor conductors covalent-network (atomic) solids - Answers covalent bonds; very hard, high melting points, poor conductors metallic solids - Answers metallic bonds; ranges from high melting points, soft, malleable--very hard, good conductors of electricity Belt of Stability - Answers the region on a graph of number of neutrons vs. protons that includes all stable nuclei; n/p ~ 1 for light nuclei, 1.5 for heavy nuclei -on the belt: stable, not radioactive -above the belt: neutron rich; Beta decay to increase the number of protons and reduce neutrons in nucleus -below the belt: neutron poor; positron emission/ electron capture to reduce the number of protons and increase the number of neutrons in nucleus alpha decay- reaction - Answers Change in A: -4 Change in Z: -2 Symbol: (4/2)He ("product") beta decay- reaction - Answers Change in A: 0 Change in Z: +1 Symbol: (0/-1)ß ("product") electron capture- reaction - Answers Change in A: 0 Change in Z: -1 Symbol: (0/-1)ß ("reactant") positron emission- reaction - Answers Change in A: 0 Change in Z: -1 Symbol: (0/1)ß ("product") radioactivity - Answers spontaneous emission of high energy radiation and particles Stellar Nucleosynthesis - Answers 1. alpha particle fusion 2. continued fusion and other nuclear reactions produce heavier nuclides in cores of stars Supernova - Answers release of free neutrons initiates new kinds of nuclear reactions: 1. neutron capture 2. beta decay positron - Answers particle with mass of an electron, positive charge Balancing Nuclear Equations - Answers 1. sum of masses of reactants = sum of masses of products 2. sum of protons of reactants = sum of protons of products mass defect - Answers difference between mass of stable nucleus and masses of individual particles that comprise (m in E=mc^2) half-life - Answers the time it takes for the amount of a substance undergoing decay to decrease by half average atomic mass - Answers the weighted average of the masses of an element's stable isoptopes atomic emission spectra - Answers characteristic patterns of bring lines produced when atoms are vaporized in high temperature flames or electrical discharges atomic absorption spectra - Answers characteristic patterns of dark lines produced when an external source of radiation passes through free gaseous atoms quantum theory - Answers energy is absorbed/emitted in discrete quantities (photons) Planck's constant - Answers 6.626*10^-34 J/sec de Broglie - Answers electrons behave like waves; wavelength= h/mv Calculating wavelength - Answers wavelength(frequency)=c Calculating energy of a photon - Answers E=(hc)/wavelength; *Energy and wavelength are inversely related Photoelectric effect - Answers work function: hv(0)=hv-KE(electron); The emission of electrons from a metal caused by light striking the metal principal quantum number (n) - Answers indicates relative energy of an orbital and its distance to the nucleus (electron shell); n= 1,2,3,4.... angular momentum quantum number (l) - Answers indicates shape of orbitals; l= 0,1,2,3...(n-1) s=0, p=1, d=2, 3=f magnetic quantum number (ml) - Answers indicates orientation of an orbital; ml= -l, -(l-1), -(l-2)...0...(l-2), (l-1), l Hund's Rule - Answers every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin. Aufbau Principle - Answers electrons occupy the orbitals of lowest energy first Electron Configuration of Ions - Answers gain/lose electrons to achieve noble gas configuration; cations versus anions isoelectronic - Answers identical electron configuration Electron Configuration Anaomolies - Answers 1/2 filled and completely filled d-subshells: ex. Cr- 3d5 4s1; ex. Cu- 3d10 4s1 Pauli exclusion principle - Answers An atomic orbital may describe at most two electrons, each with opposite spin direction Cations of Transition Metals - Answers loss of valence electrons (s) and sometimes (d); ex. Fe- [Ar] 3d6 4s2-- Fe2+ - [Ar] 3d6 -- Fe3+ - [Ar] 3d5 Size of Ions - Answers AnionsCations Atomic Radius - Answers derived indirectly by measuring distance b/w bonded atoms in molecules; increases down and from right to left across periodic table Ionization Energy - Answers energy required to remove first electron from a gaseous atom; increases up and from left to right across periodic table IE1 Exceptions - Answers Group 2 and 13: p electron experiences less effective nuclear charge than an s electrons in its shell and requires less energy to be removed; Group 15 and 16: repulsion between paired electrons raises energy, which means less energy must be added to ionize one of them Electronegativity - Answers relative ability of an atom to attract electrons in a bond to itself; increases up and from left to right across periodic table Formal Charges - Answers (# valence electrons)-(# of bonds)-(# lone pairs) Exceptions to Octet Rule - Answers 1. odd number of electrons, i.e. NO, NO2 2. less than octet, i.e. BeCl2, BF3 3. Expanded octet: many compounds and polyatomic ions with atoms in 3rd period and up, i.e. SF6, SO4 2-, PO4 3- Bond Polarity - Answers a measure of how equally or unequally the electrons in any covalent bond are shared; direction of polarity indicated by arrow, degree of polarity depends on differences in electronegativity; polarity increases with change in electronegativity Radical Species - Answers molecule with unpaired electron -- incomplete octet; i.e. O2, NO Bond Order - Answers The number of bonding pairs in a covalent bond; increased bond order= decreased bond length=increased bond energy Bond Lengths - Answers greater bond length=weaker bond; length depends on 1. identity of atoms and 2. number of bonds between atoms Bond Energies - Answers energy needed to break one mol covalent bonds in gas phase; magnitude of energy required to break bond= negative magnitude of energy released in forming bond VSEPR Theory - Answers valence electron pairs surrounding an atom mutually repel each other, and will therefore adopt an arrangement that minimizes this repulsion, thus determining the molecular geometry Steric Number - Answers SN= (# atoms bonded to central atoms) + (# lone pairs on central atom) Finding Electron-Pair Geometry - Answers 1. Draw Lewis Structure 2. Determine Steric Number (SN) Central Atom with NO lone pairs - Answers Molecular geometry will equal electron-pair geometry Central Atom WITH lone pairs - Answers molecular geometry will not equal electron-pair geometry; 1. Determine electron-pair geometry by counting bonds and electron pairs together 2. Look at bonds only for molecular geometry Molecular Geometry - Answers molecular geometry: linear - Answers molecular geometry about a central atom with a steric number of 2, no lone pairs; 180º molecular geometry: trigonal planar - Answers molecular geometry about a central atom with a steric number of 3, no lone pairs; 120º molecular geometry: tetrahedral - Answers steric number of 4, no lone pairs; 109.5º molecular geometry: trigonal bipyramidal - Answers steric number of 5, no lone pairs, three atoms occupy equatorial sites while two other atoms occupy axial sites above/below equatorial plane; 90, 120, and 180º molecular geometry: octahedral - Answers steric number of 6, no lone pairs, all six sites are equivalent; 90 and 180º molecular geometry: bent - Answers steric number of 3 with one lone pair OR steric number of 4 with two lone pairs; electron pair geometry: trigonal planar; 120º molecular geometry: trigonal pyramidal - Answers steric number of 4, one lone pair; electron pair geometry: tetrahedral; 109.5º molecular geometry: square pyramidal - Answers steric number of 6, one lone pair; atoms occupy four equatorial sites and one axial site; 90 and 180º molecular geometry: square planar - Answers steric number of 6 with two lone pairs; atoms occupy four equatorial positions while lone pairs occupy axial sites; 90 and 180º chiral molecules - Answers not super-imposable upon its mirror image or lacks an internal plane of symmetry London Dispersion Forces - Answers the intermolecular attraction resulting from the uneven distribution of electrons and the creation of temporary dipoles; weakest, only significant when no other forces present (non-polar covalent molecules, single atoms); larger electron cloud leads to greater dispersion forces Temporary (Induced) Dipole - Answers separation of charge produced in an atom or molecule by a momentary uneven distribution of electron Polarizability - Answers relative ease with which the electron cloud in a molecule, ion, or atom can be distorted, inducing a temporary dipole Factors Affecting Dispersion Strength - Answers 1. size of atoms or molecules: larger--more polarizable--dispersion strength increases 2. shape: increased surface area--increased interactions between molecules; linear molecules have higher dispersion than branched Viscosity - Answers measure of resistance to flow of a fluid Induced Dipoles - Answers proximity of polar molecule induces a dipole in a nonpolar molecule