Alkynes
Chapter Name : Hydrocarbons |
Sub Topic Code : 102_11_13_04_02 |
Topic Name : Alkynes |
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Sub Topic Name : Structure Of Triple Bond |
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Introduction
A triple bond in chemistry is a chemical bond between two chemical elements involving six bonding electrons instead of the usual two in a covalent single bond. The most common triple bond is that between two carbon atoms, can be found in alkynes. Triple bonds are also common with phosphorus atoms. Other functional groups containing a triple bond are cyanides and isocyanides. Some diatomic molecules, such as dinitrogen and carbon monoxide are also triple bonded.
Pre-Requisites:
Triple Bond
Activity:
Salts of hydrocyanic acid.
Real Life Question:
What are alkynes?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Atomic orbital | An atomic orbital is a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| acetylene | An alkyne is a hydrocarbon containing a triple carbon-carbon bond. |
Real life uses :
Alkynes are used in welding gases - used to be called oxy-acetylene welding
Places to visit :
Chemistry laboratory.
Practical examples around us
| Examples | Explainations |
|---|---|
| Cyanide | Cyanide is any chemical compound that contains monovalent combining group CN. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. |
What you learn in Theory:
The type of bonding can be explained in terms of orbital hybridization. In the case of acetylene each carbon atom has two sp orbitals and two p-orbitals. The two sp orbitals are linear with 180° angles and occupy the x-axis (Cartesian coordinate system). The p-orbitals are perpendicular on the y-axis and the z-axis. When the carbon atoms approach each other the sp orbitals overlap to form a sp-sp sigma bond. At the same time the pz-orbitals approach and together they form a pz-pz pi-bond. Likewise, the other pair of py-orbitals forms a py-py pi-bond. The result is formation of one sigma bond and two pi bonds.
What you learn in Practice:
Triple bonds are stronger than single bonds or double bonds and they are also shorter. The bond order is three.