# Step 1: Bond-Line and 3D Structures ## 1. Propane: Bond-Line and 3D Geometry **Bond-line Drawing:** Propane is a straight-chain alkane with three carbon atoms. ``` CH3-CH2-CH3 ``` Bond-line style: ``` /\ ``` Each vertex and line end is a carbon atom. Hydrogens are not shown explicitly. **3D Geometry Drawing:** - All three carbon atoms are in the same plane. - Show one C–H bond as a solid wedge (out of the plane), one as a dashed wedge (behind the plane), and the rest as lines (in the plane). Example: ``` H H \ / C / \ H—C C—H / \ H H ``` 3D version (showing one C atom, e.g., the central one, with wedges): ``` H | H—C—C—C—H | | H H (wedges showing one H out of plane, one behind) ``` **Explanation:** - **Bond-line**: Shows the carbon backbone simply. - **3D geometry**: Illustrates tetrahedral geometry at carbon centers and spatial arrangement. --- ## 2. Propane: Newman Projection, Staggered Conformation - Look down the C1–C2 bond (or C2–C3; propane is symmetric). - **Front carbon (circle):** C2 - **Back carbon (behind):** C3 Staggered conformation shows hydrogens as far apart as possible. ``` H \ C / \ H—C C—H \ / H Newman projection (staggered): H | H — C — H (front; dot) | H (viewing down C2–C3) ``` Newman projection: ``` H \ C / \ H—C C—H / \ H H Newman (down C2–C3, staggered): H \ | H — ● — H | H ``` **Explanation:** - **Newman projection**: Looks down a bond; shows spatial orientation of groups. - **Staggered**: Hydrogens on the front and back carbons are maximally separated. --- ## 3. Propane: Newman Projection, Eclipsed Conformation - Same view as above, but back hydrogens are aligned with front hydrogens. Newman projection (eclipsed): ``` H \ | H — ● — H | H (back hydrogens directly behind front hydrogens) ``` **Explanation:** - **Eclipsed**: Hydrogens on the back carbon are directly behind those on the front carbon (least stable conformation). --- ## 4. Butane: All Staggered Conformers (Newman, down C2–C3) - Draw Newman projections looking down C2–C3. - Butane: CH3–CH2–CH2–CH3 **Staggered conformers:** 1. **Anti:** CH3 groups 180° apart (most stable) 2. **Gauche:** CH3 groups 60° apart (there are two possible gauche conformers, mirror images) **Drawings:** - **Anti (CH3 groups opposite):** ``` H H \ / ●-----● / \ CH3 CH3 ``` - **Gauche (CH3 groups 60° apart):** ``` CH3 H \ / ●-----● / \ H CH3 ``` - **Other Gauche (mirror image):** ``` H CH3 \ / ●-----● / \ CH3 H ``` **Explanation:** - **Staggered conformers**: Groups are as far apart as possible, minimizing torsional strain. - **Anti**: Methyl groups farthest apart. - **Gauche**: Methyl groups 60° apart. --- ## 5. 1,1-Dibromoethane: Bond-Line and 3D Geometry **Bond-line Drawing:** - Structure: CH3–CHBr2 Bond-line: ``` Br | CH3-C-Br ``` **3D Geometry:** - Both Br on the same carbon (C1 or C2), with one Br and the two carbons in the plane, the other Br above or below (use wedge/dash). Example: ``` Br | H3C—C—Br / \ H H (one Br in plane, one as wedge/dash) ``` **Explanation:** - **Bond-line**: Shows connectivity. - **3D**: Shows geometry around the substituted carbon. --- ## 6. 1,2-Dibromoethane: Bond-Line and 3D Geometry **Bond-line Drawing:** - Structure: BrCH2–CH2Br Bond-line: ``` Br—CH2—CH2—Br ``` **3D Geometry:** - Both carbons and both Br in the plane. Example: ``` Br Br | | C — C | | H H ``` **Explanation:** - **Bond-line**: Shows Br on both carbons. - **3D**: Both Br and both C in the plane for clarity. --- ## 7. cis-2,3-Dibromo-2-butene: Bond-Line - Structure: CH3–C(Br)=C(Br)–CH3 - Both Br on the same side of the double bond. Bond-line: ``` CH3 | Br—C=C—Br | CH3 ``` Or more typically: ``` Br Br \ / C=C / \ CH3 CH3 ``` **Explanation:** - **cis**: Both Br atoms on the same side of the double bond. --- ## 8. trans-2,3-Dibromo-2-butene: Bond-Line - Structure: CH3–C(Br)=C(Br)–CH3 - Br on opposite sides of the double bond. Bond-line: ``` Br CH3 \ / C = C / \ CH3 Br ``` **Explanation:** - **trans**: Br atoms on opposite sides of the double bond. --- # Final Answer Above, each question is answered with both the required drawings and explanations for each part as requested. If you need the actual hand-drawn images or more compact representations, let me know.