Organic Chemistry Lecture 1 PDF

lecture 1 ORGANIC CHEMISTRY\ ALKANES  Al Turath University  College of Pharmacy  organic chemistry Ι  first stage  Assistant lecturer : Asmaa Edrees  Chemical bonds The ionic bond results from the transfer of electrons The covalent bond results from the sharing o...

lecture 1 ORGANIC CHEMISTRY\ ALKANES  Al Turath University  College of Pharmacy  organic chemistry Ι  first stage  Assistant lecturer : Asmaa Edrees  Chemical bonds The ionic bond results from the transfer of electrons The covalent bond results from the sharing of electrons The covalent bond is typical of the compounds of carbon; it is the bond of chief importance in the study of organic chemistry. A covalent bond to form two atoms must be located so that an orbital of one overlaps an orbital of the other; each orbital must contain a single electron. When this happens, the two atomic orbitals merge to form a single bond orbital which is occupied by both electrons Hybrid Orbitals When carbon atoms form bonds with each other, we describe the resulting bonds using hybrid orbitals, which are formed by mixing (hybridizing) the carbon’s atomic orbitals. When carbon atoms bond to 4 other atoms, the 2s orbital and all three 2p orbitals in the valence shell combine to produce four sp3 hybrid orbitals: 1. sp Hybridization Carbon can have an sp hybridization when it is bound to two other atoms with the help of two double bonds or one single and one triple bond. When the hybridization occurs the molecules have a linear arrangement of the atoms with a bond angle of 180°. Example: Hybridization of. 2. sp2 Hybridization A carbon atom is sp2 hybridized when bonding takes place between 1 s-orbital with two p orbitals. There is a formation of two single bonds and one double bond between three atoms. The hybrid orbitals are placed in a triangular arrangement with 120° angles between bonds. Example: 3. sp3 Hybridization When the carbon atom is bonded to four other atoms the hybridization is said to be sp3 type. Here 1 s orbital and 3 p orbitals in the same shell of an atom combine to form four new equivalent orbitals. The arrangement is tetrahedral with a bond angle of 109.5o. Example: Hybridization of CH4 (Methane) Properties of Alkanes:-  Alkanes are nonpolar, which makes them insoluble in water. However, they are soluble in nonpolar solvents.  Alkanes have densities from 0.62 g/mL to about 0.79 g/mL, which is less than the density of water (1.0 g/mL).  1-4 carbon atoms (meth. – But.) are gases at room temperature and are widely used as heating fuels.  5-9 carbon atom (pent. – Octa.) liquids at room temperature. They are highly volatile and useful in fuels such as gasoline.  9-17 carbon atoms have higher boiling points and are found in kerosene, diesel, and jet fuels.  18 and more carbon atoms They are waxy solids at room temperature. They are known as paraffin. They are used in waxy coatings added to fruits and vegetables to retain moisture, inhibit mold, and enhance appearance.  25 and more atoms of carbon Vaseline, is a semisolid mixture of hydrocarbons used in ointments, cosmetics, and as a lubricant homework Question 1: What is the common name for a hydrocarbon with the molecular formula C4H10? Question 2: Name the following compound: CH3CH2CH2CH2CH2CH3? Question 3: Name the compound according to IUPAC Question 4: Draw the line-angle structural formula as a zigzag line to n-pentane, isopentane, and neo-pentane.  "don't give up on science... it is science that makes life... and whoever stops learning... stops living." thank you for listening