Notes On Aldehydes And Ketones: Structure Of The Carbonyl Group And Physical Properties - CBSE Class 12 Chemistry
In carbonyl group, the Carbon - Oxygen double bond is polar in nature due to the electro negativity difference between Carbon and Oxygen. The carbon-oxygen sigma bond is produced by the overlap of one sp2 orbital of carbon with p-orbital of oxygen and, the Carbon-Oxygen pi bond is formed by the sideway overlap of the p-orbitals of Carbon and Oxygen. At room temperature, formaldehyde is a gas and acetaldehyde is a volatile liquid. Other aldehydes and ketones are liquids (or) solids at room temperature. Aldehydes and ketones have higher boiling points, than hydrocarbons and ethers of comparable molecular weights due to the weak inter-molecular dipole-dipole interactions. Aldehydes and ketones are soluble in the usual organic solvents, like benzene, ether and chloroform. Lower aldehydes and ketones such as formaldehyde, acetaldehyde and acetone, are miscible in water in all proportions because of their ability to form hydrogen bonding with water. The lower aldehydes and ketones have a characteristic pungent odour. With an increase in the size of the molecule, the odour becomes less

#### Summary

In carbonyl group, the Carbon - Oxygen double bond is polar in nature due to the electro negativity difference between Carbon and Oxygen. The carbon-oxygen sigma bond is produced by the overlap of one sp2 orbital of carbon with p-orbital of oxygen and, the Carbon-Oxygen pi bond is formed by the sideway overlap of the p-orbitals of Carbon and Oxygen. At room temperature, formaldehyde is a gas and acetaldehyde is a volatile liquid. Other aldehydes and ketones are liquids (or) solids at room temperature. Aldehydes and ketones have higher boiling points, than hydrocarbons and ethers of comparable molecular weights due to the weak inter-molecular dipole-dipole interactions. Aldehydes and ketones are soluble in the usual organic solvents, like benzene, ether and chloroform. Lower aldehydes and ketones such as formaldehyde, acetaldehyde and acetone, are miscible in water in all proportions because of their ability to form hydrogen bonding with water. The lower aldehydes and ketones have a characteristic pungent odour. With an increase in the size of the molecule, the odour becomes less

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