Chapter 1 Carbon Compounds and Chemical Bonds
Chapter 1 Carbon Compounds and Chemical Bonds. (Covered material: 1.1 - 1.8; 1.12 - 1.17)
1. Structural Theory – most fundamental theory of Organic Chemistry (developed independently by A. Kekule, A. Couper and A. Butlerov between 1858 and 1861). Organic Compounds – compounds of carbon and hydrogen. Other elements frequently found in organic compounds are: oxygen, nitrogen and halogens (F, Cl, Br, I); less frequently found are: sulfur and phosphorus. Review Periodic Table for determining valence (ability to form a fixed number of bonds). “Organic elements” can form the following number of bonds: Element # of bonds H 1 C 4 N 3 O 2 Hal 1
Carbon may form a single, double and triple bonds to another carbon:
C
C
C
C
C
C
2. Structural or Constitutional Isomers: compounds with the same molecular formula, but different atom connectivity.
C2H6O
Two different compounds with different physical & chemical properties: Ethyl alcohol (ethanol): B.P. 78.5 oC (liquid) M.P. –117.3 oC Reacts with alkaline metals. Dimethyl ether: -24.9 oC (gas!) -138 oC Does not
How many isomers can you draw for:
C4H10O
C4H8O
3. Chemical Bonds Ionic: forms by a complete transfer of one or more electrons from one atom to another to form ions (cation and anion). Forms between typical metal and non-metal due to a significant difference in electronegativity (ability of atom to attract electrons; refer to table 1.2).
LiF
Covalent: forms by sharing electrons between two atoms (polar covalent and non-polar covalent). Forms between non-metals. Electronegativity difference ∆ EN for two elements: ∆ EN > 1.2 Ionic Bond 0.4 < ∆ EN < 1.2 Covalent Polar ∆ EN < 0.4 Covalent Non-polar
H2 CH4
Octet Rule: to form compounds atoms gain, lose or share electrons in order to achieve a stable electron configuration of 8 electrons in the outer shell. It is only 2 electrons for H, and elements beyond the second period may have more than 8 electrons. It is important to
1. Structural Theory – most fundamental theory of Organic Chemistry (developed independently by A. Kekule, A. Couper and A. Butlerov between 1858 and 1861). Organic Compounds – compounds of carbon and hydrogen. Other elements frequently found in organic compounds are: oxygen, nitrogen and halogens (F, Cl, Br, I); less frequently found are: sulfur and phosphorus. Review Periodic Table for determining valence (ability to form a fixed number of bonds). “Organic elements” can form the following number of bonds: Element # of bonds H 1 C 4 N 3 O 2 Hal 1
Carbon may form a single, double and triple bonds to another carbon:
C
C
C
C
C
C
2. Structural or Constitutional Isomers: compounds with the same molecular formula, but different atom connectivity.
C2H6O
Two different compounds with different physical & chemical properties: Ethyl alcohol (ethanol): B.P. 78.5 oC (liquid) M.P. –117.3 oC Reacts with alkaline metals. Dimethyl ether: -24.9 oC (gas!) -138 oC Does not
How many isomers can you draw for:
C4H10O
C4H8O
3. Chemical Bonds Ionic: forms by a complete transfer of one or more electrons from one atom to another to form ions (cation and anion). Forms between typical metal and non-metal due to a significant difference in electronegativity (ability of atom to attract electrons; refer to table 1.2).
LiF
Covalent: forms by sharing electrons between two atoms (polar covalent and non-polar covalent). Forms between non-metals. Electronegativity difference ∆ EN for two elements: ∆ EN > 1.2 Ionic Bond 0.4 < ∆ EN < 1.2 Covalent Polar ∆ EN < 0.4 Covalent Non-polar
H2 CH4
Octet Rule: to form compounds atoms gain, lose or share electrons in order to achieve a stable electron configuration of 8 electrons in the outer shell. It is only 2 electrons for H, and elements beyond the second period may have more than 8 electrons. It is important to