Understanding Hybridization: Ethane, Ethene, and Ethyne Explained
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Dec 10, 2024
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Name: ZIGASHANE Robert Access Number: A97165 Reg. Number: J22C00/080 HEC Science / Biological Chemistry/Assignment Foundation of Organic and Analytical chemistry Assignment 1 Question One: a)Describe how hybridization takes place in (i)Ethane =>(C2H6) Ethane basically consists of two carbon atoms and six hydrogen atoms. However, carbon will be the central atom and its orbitals will take part in hybridization. During the formation of C2H6, 1 s orbital and px, py, and pz orbitals undergo sp3hybridization. The result become a formation of 4 orbitals which are hybridized foe each atom of carbon, and the hybridized molecular make different born between the electron. One of four sp3hybrid orbitals, one of one carbon atom overlap with 1 s-orbital of the hydrogen to make three sigma bonds; and the last orbital will overlap with a sp3of other atom to make a sigma bond between 2 carbon atoms. So, In C2H6, 1 s orbital and three p-orbitals (px, py, pz) take part in hybridization, there is a formation of four sp3 orbitals that are hybridized and during the hybridization of ethane four identical bonds are formed. (ii)Ethene During the formation of CH2=CH2, it’s electronic configuration (1s2 2s22p12p1) will change to an excited state and change to 1s22s1 2px12py12pz1. When excited, since carbon needs electrons to form bonds one of the electrons from 2s2orbital will be moved to the empty 2pz orbital to form 4 unpaired electrons. Meanwhile, out of 2s, 2px, 2py, and 2pz orbitals in carbon, only 2px, 2py, and 2s take part in hybridization. One 2pz orbital remains unchanged. This leads to the formation of three sp2 hybridized orbitals. The hybrid orbitals look like sp3 orbitals, but they are sp2 orbitals as they are fatter and shorter. The molecular orbitals after hybridization form different bonds between the electrons. One carbon atom overlaps the sp2 orbital of another carbon atom to form sp2 –sp2 sigma bond. The two sp2 hybrid orbitals get overlapped by two hydrogen atoms containing unpaired electrons. A pi bond is formed by the unhybridized 2pz orbitals of each carbon atom. By conclusion, in ethene molecule, the carbon atoms are sp2 hybridized. One unpaired electron in the p orbital remains unchanged; in ethylene, each carbon combines with three other atoms rather than four;there is a formation of a sigma bond and a pi bond between two carbon atoms. (iii)Ethyne the electronic configuration of carbon represented as 1s2 2s2 2p2. When it get exited, one of the electron from 2s orbital move to the 2pz orbital and the electronic configuration change. Meanwhile, the CH molecule has only 1 hydrogen atom, therefore the 2s1 and the 2pz1 orbitals get hybridized, further,this leads to the formation of 4 sp hybridized orbitals wherein each CH molecule form 2 hybridized
orbitals. During hybridization, C-C a sigma bond is formed when one sp orbital overlaps from each of the carbons and two C-H bonds are created when second sp orbital on each carbon overlaps with 1s orbital of hydrogen. In this, the carbon atom become two half-filled 2p orbitals, two pairs of p orbitals do not participate in the hybridization and instead form two pi bonds resulting in the creation of a triple bond. so, In the formation of C2H2, the carbon atom needs extra electrons to form 4 bonds with hydrogen and other carbon atoms. As a result, one 2s2 pair is moved to the empty 2pz orbital. The 2s orbital in each carbon hybridizes with one of the 2p orbitals and forms two sp hybrid orbitals. Ethyne has a triple bond between the two carbon atoms. b)Discuss the nature of the carbon-carbon bonds in ethyne as compared to ethane Ethane has sp3 hybridized carbon atoms, while ethyne has sp hybridized carbon atoms. Ethane have only one bond (sigma bond) between its Carbone, but ethyne has three: one sigma bond and two pi bonds. Therefore, there are no un-hybridized p orbitals in those carbon atoms; Carbon-Carbon bond in ethane is more stable than in ethyne. Each carbon atom has one hydrogen atom bonded via a single bond, but every Carbone in ethane have 3 hydrogen atoms bonded via three single bonds. Question Two: a)Name the following compounds according to the IUPAC rules of naming organic compounds (ii) (i) (iii) H3C CH CH2CH3CH(CH3)2(iv) (v) (vi) CH2CH2CH3b)Draw the structures of the following compounds 1-methylethyl-Cyclohexane or 1-propyl-cyclohexane (ii)3,4-dimethyl-pent-2-ene (iii)2-ethyl-pentane (iv)1-dimethyl-cyclobutane (V)4-methyl-heptane (vi)1-propyl-cyclopent-1,3-diene
(i) 2,2,3-trimethylpentane CH3 CH3 H3C-C- CH-CH2CH3 CH3 Or (iii) 3,3,6-trimethylcyclohex-1-ene (iii) (iv) 4-ethyl-3,5-dimethylheptane CH2CH3 CH3CH2-CH-CH-CH-CH2CH3 CH3 CH3 or 1,2,4-trimethylcyclopent-1-ene