In allene $(C_3H_4)$ the type(s) of hybridisation of the carbon
atoms, is (are)
- $sp \, and \, sp^3$
- $sp \, and \, sp^2$
- $ only \, sp^3$
- $sp^2 \, and \, sp^3$
The Correct Option is B
Approach Solution - 1
Allene is the name given to propdiene, \(_{ \, \, \, \, \, \, \, \, Allene}^{H_2C = C = CH_2}\)
Hybridisation of an atom is determined by determining the number of hybrid orbitals at that atom which is equal to the number of sigma \((s)\) bonds plus number of lone pairs at the concerned atom.
Pi\((p)\) bonds are not formed by hybrid orbitals, therefore, not counted for hybridisation.
Here, the terminal carbons have only three sigma bonds associated with them, therefore, hybridisation of terminal carbons is \(sp^3\). The central carbon has only two sigma bonds associated, hence hybridisation at central carbon is sp.
So, the correct answer is (B): sp and sp2
Approach Solution -2
In the compound, the central atom is combined with other atoms with the help of two sigma bonds and two pi bonds, the hybridization for the compound is sp. The terminal carbon on the other hand, is attached to the carbon atom and also hydrogen by 3 sigma and 1 pi bond, the hybridization will be sp2.
So, the correct answer is (B): sp and sp2
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Concepts Used:
Alkenes
Alkenes
In organic chemistry, an alkene is a hydrocarbon containing a carbon-carbon double bond.[1]
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.
Read More: Ozonolysis
IUPAC Nomenclature of Alkenes
- An alkene or cycloalkene is indicated by the suffix (ending) ene.
- For the root name, the longest chain must include both carbon atoms of the double bond.
- The root chain must be numbered beginning at the end closest to a double bond carbon atom. If the double bond is in the chain's centre, the nearest substituent rule is used to determine where the numbering begins.
- If the compound contains more than one double bond, it is named with a diene, triene, or equivalent prefix indicating the number of double bonds, and each double bond is assigned a locator number.
Read More: Unsaturated Hydrocarbon