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Exam 2 Chemistry Key Concepts

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Terms in this set (27)

  • Molecular formula vs. condensed vs. Lewis vs. skeletal structures

    Molecular formula shows types and numbers of atoms. Condensed groups atoms by bonds. Lewis shows all bonds and lone pairs. Skeletal shows carbon skeleton with implied hydrogens.

  • Identify functional groups: alkanes, alkenes, alkynes

    Alkanes have single bonds, alkenes have double bonds, alkynes have triple bonds between carbons.

  • Functional groups: alcohol, amine, ether, alkyl halide, aromatic

    Alcohol: -OH group; Amine: -NH2 or derivatives; Ether: R-O-R; Alkyl halide: halogen attached to alkyl; Aromatic: benzene ring structure.

  • Carbonyl functional groups: amides, carboxylic acids, aldehydes, ketones, esters

    All contain C=O. Amides: C=O attached to N; Carboxylic acids: C=O and -OH; Aldehydes: C=O at end of chain; Ketones: C=O within chain; Esters: C=O adjacent to O-R.

  • IUPAC naming basics for alkanes, alkenes, alkynes

    Name longest carbon chain, number to give substituents lowest numbers, use suffixes -ane, -ene, -yne for single, double, triple bonds respectively.

  • Bond length vs. bond strength relationship

    Shorter bonds are generally stronger. Triple bonds are shorter and stronger than double, which are shorter and stronger than single bonds.

  • Alkyl substituent naming examples

    Common alkyl groups: methyl (CH3-), ethyl (C2H5-), propyl (C3H7-), named by removing -ane and adding -yl.

  • Halogen substituent naming

    Halogens as substituents are named as prefixes: chloro (Cl), bromo (Br), fluoro (F), iodo (I).

  • Types of isomers: structural and stereoisomers

    Structural isomers differ in connectivity. Stereoisomers have same connectivity but differ in spatial arrangement.

  • Stereoisomers: cis/trans and chiral molecules

    Cis/trans differ by relative positions around double bonds or rings. Chiral molecules have non-superimposable mirror images due to chiral centers.

  • Identifying chiral centers

    A chiral center is a carbon bonded to four different groups, leading to non-superimposable mirror images (enantiomers).

  • Enantiomers

    Enantiomers are pairs of chiral molecules that are non-superimposable mirror images with identical physical properties except optical activity.

  • Omega and X:X notation for fatty acids

    Omega indicates position of first double bond from methyl end. X:X shows number of carbons and double bonds (e.g., 18:1).

  • Saturated vs. monounsaturated vs. polyunsaturated fatty acids

    Saturated: no double bonds; monounsaturated: one double bond; polyunsaturated: multiple double bonds.

  • Enthalpy (ΔH) and exothermic vs. endothermic reactions

    ΔH is heat change. Exothermic releases heat (ΔH negative). Endothermic absorbs heat (ΔH positive).

  • Free energy (ΔG) and spontaneity

    ΔG negative means spontaneous (exergonic), positive means non-spontaneous (endergonic).

  • Ways to increase reaction rate

    Increase temperature, add more reagents, or use a catalyst.

  • Categories of organic reactions

    Synthesis: building molecules; decomposition: breaking down; exchange/displacement: swapping parts.

  • Specific organic reaction types

    Includes redox, combustion, addition (hydration, hydrogenation), condensation, and hydrolysis.

  • Monosaccharide classification: triose, tetrose, pentose, hexose

    Classified by carbon number: triose (3C), tetrose (4C), pentose (5C), hexose (6C).

  • Aldose vs. ketose sugars

    Aldose has aldehyde group at C1; ketose has ketone group usually at C2.

  • Diastereomers, enantiomers, and epimers in sugars

    Enantiomers: mirror images; diastereomers: not mirror images; epimers: differ at one chiral center.

  • Anomeric carbon and alpha/beta designation

    Anomeric carbon is the new chiral center formed in cyclic sugars. Alpha: OH down; Beta: OH up on anomeric carbon.

  • Glycosidic bond formation in disaccharides

    Two monosaccharides join by condensation, forming a glycosidic bond which can be alpha or beta with specific carbon numbering.

  • Polysaccharides: storage vs. structural

    Storage: starch, glycogen; Structural: cellulose, chitin.

  • Starch components

    Starch is plant glucose storage made of amylose (linear) and amylopectin (branched).

  • Gas laws: Boyle’s, Charles’, Gay-Lussac’s (conceptual)

    Boyle’s Law: pressure inversely proportional to volume; Charles’ Law: volume proportional to temperature; Gay-Lussac’s Law: pressure proportional to temperature.