CHEM219 / CHEM 219 Module 1: (Latest Update 2026 / 2027) Principles of Organic Chemistry with Lab | Questions & Answers | Grade A | 100% Correct – Portage Learning

CHEM219 / CHEM 219 Module 1: (Latest Update 2026 / 2027) Principles of Organic Chemistry with Lab | Questions & Answers | Grade A | 100% Correct – Portage Learning 2026 / 2027 Academic Year Q: On a piece of scratch paper, write out the Lewis Dot Diagram for each of the indicated elements and determine the following for each: Answer a) The number of Lone Pairs the atom possesses in its valence shell.b) The number of Unpaired Electrons the atom possesses in its valence shell.c) The number of bonds the atom will form. Oxygen Carbon Hydrogen Nitrogen Oxygen - a) 2 b) 2 c) 2 Carbon - a) 0 b) 4 c) 4 Hydrogen- a) 0 b) 1 c) 1 Nitrogen - a) 1 b) 3 c) 3 Q: Classify the bonding between the given pairs of atoms as ionic, covalent, or polar covalent. Use the table of electronegativities shown below to help with the classification. a. Br and Br b. K and Cl c. P and Cl d. C and O e. Na and Br Answer a. Br-Br: Electronegativity difference () = 0 = COVALENT (or pure covalent) b. K-Cl: () = 2.2 = IONIC c. P-Cl: ()= 0.9 = POLAR COVALENT d. C-O: ()= 1.0 = POLAR COVALENT e. Na-Br: () = 1.8 = POLAR COVALENT Q: Define the term constitutional isomer. Answer Two (or more) different chemical compounds with the same molecular formula but different connectivity between the atoms in their structural formulae. Q: Explain (using specific evidence) what makes the following two compounds constitutional isomers of one another: Answer Both compounds have a MF of C3H6O - same MF. Compound "a" has a 3-carbon chain with a C=O in the middle. No H atom connected to C of C=O. Compound "b" has a 3-carbon chain with a C=O at the end. There is an H attached to the C of the C=O. Q: What is the relationship between the compounds shown? Are they the same compound, constitutional isomers, or two different compounds that are not related to one another? Explain. Answer Different compounds that are not related. They have different MF - (a) C3H8O, (b) C3H6O. Q: Identify each of the following carbon skeletons as linear (continuous), branched, or cyclic. Answer a) Branched b) Linear (continuous) c) Cyclic Q: On a piece of scratch paper, write out structural formulae for all of the constitutional isomers possible for the MF C3H6F2. How many isomers are possible for this formula? Answer 4 Q: Characterize each of the following structural formula representations as either a dash, condensed, super-condensed, or bond-line formula: Answer a) Super-Condensed b) Condensed c) Bond-line d) Dash Q: Write the molecular formula for each of the compounds whose bond-line formulae are given below. Answer a) C5H10 b) C3H8O c) C4H10O Q: Which bond-line formula shown below represents a constitutional isomer of CH3CH2CH2CH2CH3? Answer (b) Q: Which of the following structures does NOT have the molecular formula C6H14? Answer (d) Q: The structural formula: Has what molecular formula? Answer (c) C7H14 Q: The compound carbon monoxide has the following structural formula: What is the formal charge on the carbon and the oxygen? Show your calculation. What is the overall charge on the molecule? Answer Carbon = 4-(2+3) = -1 Oxygen = 6-(2+3) = +1 Overall = FC Carbon + FC Oxygen = [-1 + (+1)] = 0 Q: For the following example of resonance: Answer Which structure (a or b) represents a "major" resonance contributor to the hybrid? Briefly explain why. Structure "a" is a major contributor. All of the atoms have complete valences and in addition, all of the atoms have a formal charge of zero (All of the atoms are meeting their LDD bonding pattern). Q: Describe how individual resonance structures impact the true structure of a molecule or polyatomic ion. Answer Each contributing individual resonance structure contributes characteristics to the overall hybrid structure of the compound. The hybrid "averages" bond lengths and formal charges by delocalizing them among atoms that share them in each contributing individual resonance structure. Q: On a piece of scrap paper, draw the resonance structure "b" that would result from redistributing the electrons as shown on structure "a" in the diagram below: For your structure "b", complete the table with the information requested: Answer Oxygen: 1 lone pair, 1 single bond, 1 double bond, +1 formal charge. Carbon (1): 0 lone pair, 2 single bond, 1 double bond, 0 formal charge. Carbon (II): 1 lone pair, 3 single bond, 0 double bond, -1 formal charge. Q: Describe the shapes associated with the atomic orbitals associated with the main elements of organic chemistry. Answer S orbitals are spherical (single lobe), while P orbitals are dumbbell-shaped (two lobes). End-on overlap of atomic orbitals leads to the formation of sigma (single) covalent bonds. Sideways overlap of P orbitals leads to the formation of pi (multiple) covalent bonds. Q: Explain how bonds are formed between atoms from the perspective of atomic orbital theory. Answer Atoms form bonds by overlapping individual atomic orbitals from each atom to produce molecular (bonding) orbitals. Q: Explain the two types of atomic orbital overlap that contribute to bond formation in organic molecules. Answer Q: Using the VSEPR method, predict the molecular geometry (shape and bond angle) around the indicated atoms for the following structure: a) C(I) b) C(II) c) N d) S Answer a) C(I) = 4 bond pairs = TETRAHEDRAL, 109.5° b) C(II) = 3 bond pairs = TRIGONAL PLANAR, 120° c) N = 3 bond pairs/1 lone pair = TRIGONAL PYRAMIDAL, 107° d) S = 2 bond pairs/2 lone pairs = ANGULAR/BENT, 105° Q: Catenation Answer The process or preference of an element to link/bond with another atom of the same element. Q: Ionic bond Answer ***formed by the sharing of electrons - electronegativity diff: 0.4 (zero difference) ***the complete transfer of one or more valence electrons from one atom to another - electronegativity diff 1.8 (large) Q: (Pure) Covalent bonds Answer Q: Diatomic element Answer When an atom is more stable when bonded to another atom Q: Pure covalent bond Answer ***A bond that forms between atoms of identical electronegativity values. (aka shared electrons) - electronegativity diff 0.4 (zero) Q: Polar covalent bond Answer ***Bond that occurs when atoms are shared unequally. - electronegativity diff: Between 0.4 and 1.8 Unsaturated compound Answer Molecules that posses one or more double or triple bonds (or a ring) as part of their structure. Isomer Answer Molecules with the same molecular formula but a different structure, and therefore a different shape. - constitutional or structural isomers Formal charge formula Answer FC = group # of element - (dots + dashes) - dots = non-binding electrons (lone pair or single unpaired electrons) - dashes = bonding electrons Resonance structure Answer Two or more structural formula of a molecule with identical arrangements of atoms BUT different arrangements of electrons Major contributor Answer Ideal arrangement/structure Minor contributor Answer Less ideal arrangement/structure Non-contributor Answer - associated with P orbitals only - Pi orbital Arrangement/structure does not match or correlate with correct atoms/electrons in an element. End-on overlap molecules Answer The binding/combination of either S or P orbitals, or both Sideways orbital overlap Answer Valence shell electron pair repulsion (VSEPR) theory A tool for determining the shape around atoms in molecules based on analysis of the patterns of electrons around them. - electrons repel (want to be far apart from each other) Molecular geometry - wedge bond: project out of plane of paper (towards us) - dash bond: project behind plane of paper (away from us) - line bond: rep atoms/groups that remain in plane of paper Cation Becomes positively charged when it loses an electron Anion Becomes negatively charged when it receives an electron The properties & reactivity of an organic molecule are controlled by its composition & shape What is organic chemistry? Branch of chemistry that studies the structure, properties, composition, reaction and synthesis of organic compounds which contain carbon atoms. Catenation Ability of ab element to form bonds with itself, resulting in formation of chains, rings or complex structures. Allows for vats diversity of organic compounds in terms of reactivity and properties Why do atoms form bonds to other atoms? Energetic stability To say an atom is energetically stable means that the overall energy of the atom is lower when in the bonded state than in a non bonded state T/F Lower energy typically means greater stability? Why True b/c the electron configuration of the atom - atomic valence Valence # of bonds an atom will form to fill its valve (outermost) shell. The atom achieves stability from a full valence shell, as there is no desire to make bonds Knowing the valence of an atom is important because it indicates ... How many bonds a given atom will typically form when it combines with other elements to make a molecule What do you look at to figure out how many bonds an element will form LDD Comes from group number Unpaired electrons # of bonds the atom will form # of pairs of electrons LONE pairs or nonbonding , these do not participate in bonding Ionic bonds formed by the complete transfer of 1 or more valence electron from 1 atom to another Cation The atom that loses an electron becomes positively charged Anion The atom that gains an electron, becomes negatively charged Ion Chemical species that possesses a non-zero electrical charge. An ionic bond is the attractive force bt oppositely charged ions - an electrostatic attraction (opposites attract) How does electronegativity (X) increase increases moving towards the right and going up the PTOTE Covalent Bonds share electrons bt elements with little or no difference in their electronegativity - Heat is released when covalent bonds are formed Diatomic Elements a molecule composed of only 2 atoms of the same element. In their natural state, these elements exist as diatomic molecules rather than individual atoms b/c they are more stable in this paired form Key parameters of a covalent bond Bond strength bond length Bond strength determined by how much heat is released when covalent bond forms (atoms lose energy in form of heat), gain stability Chemical term used to describe the energy/stength of a covalent bond is known as bond enthalpy Bond length distance that described the perfect balance bt attraction and repulsion the atoms vibrate around each other at some equilibrium point, neither flying apart or fusing together What determines the number of bonds an atom can form The number of unpaired electrons Do lone pairs bond No Cation Loses electron and becomes positive Ionic bond The transfer of a valence electron to another atom Anion Gains electron and becomes negative Covalent bond Sharing of electrons Pure covalent bond Identity of atoms is the same Polar covalent bond Unequal sharing of electrons EN difference of 0 Pure covalent EN difference of 0-0.5 Covalent EN difference of 0.5-2.0 Polar covalent EN difference above 2.0 Ionic Bond order The number of bonds between atoms: 1 for a single bond, 2 for a double bond, and 3 for a triple bond Unsaturation Lack of hydrogen due to the catenation of carbon Constitutional isomers Same molecular formula, but different connectivity Heteroatoms Atoms other than C and H Condensed formula CH3CH2CH2CH3 Super-condensed formula CH3(CH2)CH3 Formal charge Atoms that do not meet the LDD bonding pattern and possess non-zero charge Calculate formal charge Group number - (Dots + Dashes) Overall charge Sum of formal charges Hybrid resonance The average of all resonance structures What gets changed in resonance Lone pairs - Multiple bonds OR Multiple bonds - Lone pairs Never single bonds Major contributors to resonance Completes the valence Orbital Space around nucleus with high probability of finding an electron Node Center of orbital, unlikely to find an electron Which orbitals are in ochem S&P (spherical and dumbell) Combination of orbitals theory A bond between atoms is due to an overlap of their atomic orbitals, resulting in a bonding molecular orbital Sigma bond End on overlap, circular symmetry around bond axis, in hybrid orbitals Pi bond Sideways overlap of orbitals 2 bonding 0 lone Linear, 180 2 bonding 1 lone angular/bent, 107 3 bonding 0 lone trigonal planar, 120 3 bonding 1 lone trigonal pyramidal, 107 2 bonding 2 lone angular/bent, 105 4 bonding 0 lone tetrahedral, 109.5 What do you count double bonds as in VSPER A single pair Linear 180° 2 BE 0 LP Angular (2 total electron pairs) 107° 2 BE 1 LP Trigonal Planar 120° 3 BE 0 BE Trigonal Pyramidal 107° 3 BE 1 LP Angular/Bent (4 total electron pairs) 105° 2 BE 2 LP Tetrahedral 109.5° 4 BE 0 LP Bond Type for 0 difference in EN? Purely Covalent (usually elements to themselves) Bond Type for 0 but /= 0.5 Covalent Bond Type for 0.5 by /= 2.0 Polar Covalent Bond Type for /= 2.0 Ionic Ionic Bond Melting Point Very High Covalent Bond Melting Point Lower than 300 C Ionic Physical State Brittle, Crystalline Covalent Physical State Solid, gas, liquid Covalent Solubility Range of solubilities Ionic Solubility Dissolves readily in polar solvents Ionic Conduction Aqueous solutions conduct electricity Covalent Conduction Aqueous solutions do NOT conduct electricity Formal Charge Formula FC = Group # - (Dots + Dashes)