The properties of the alkenes Flashcards
What type of hydrocarbons are alkenes?
Alkenes are unsaturated hydrocarbons.
What is the general formula for alkenes with one double bond?
C_nH_{2n}.
Name the first three members of the alkene homologous series.
- Ethene
- Propene
- But-2-ene
Can alkenes be branched or cyclic?
Yes, alkenes can be branched, cyclic, or contain more than one double bond.
What is the general formula for branched alkenes?
C_nH_{2n}.
True or False: Cyclic alkenes obey the general formula C_nH_{2n}.
False.
What does each carbon atom in a double bond use to form bonds?
Each carbon atom uses four electrons in its outer shell.
How many electrons are involved in sigma bonds for each carbon atom in a double bond?
Three electrons.
What type of bond is formed by the sideways overlap of two p-orbitals?
A pi bond.
What prevents rotation around the double bond in alkenes?
The pi bond locks the two carbon atoms in position.
What shape is formed around each carbon atom in a double bond?
Trigonal planar.
What is the bond angle around each carbon atom in an alkene?
120°.
How many regions of electron density are around each carbon atom in a double bond?
Three regions.
Fill in the blank: The electron density in a pi bond is concentrated _______ and _______ the line joining the nuclei of the bonding atoms.
above
below
What is the effect of the pi bond on the geometry of alkenes compared to alkanes?
It makes the geometry different because rotation is not possible around the double bond.
