We are going to study the chemistry involved in the formation of a triple bond. Examine by studying the appropriate triple bond examples of alkynes, functional groups, etc.
Lets have a look at various tripe bond examples :
So what is a triple bond? When atoms share three pairs of electrons and form a bond the resultant is a triple bond. It is said to be highly reactive with low or shorter bond length. The triple bond is represented by three parallel dashes (C≡C ). They are observed to have low melting and boiling point.
Also, it is considered that as the number of carbon increases, the melting and boiling point also increases; they are soluble in organic solvents and insoluble in water. So we will have a closer approach to the formation of the triple bond by studying molecules of various triple bond examples.
Strength of Bond: As the strength of the bond increases, the length of the bond decreases. Triple bonds are much stronger also shorter than double bonds between the same kind of atoms. The bond length is around 1.203 Å, and the energy required to break the bond is -365 kJ/mol. Bond length is observed to be inversely proportional to bond strength and bond dissociation energy.
The concept of hybridization is very useful in understanding the concept of shape and molecular geometry of molecules. So the hybridization is the intermixing of atomic orbitals leading to the formation of the desired new hybrid orbital. The sigma bond is formed between the sp orbital of the one-carbon with that of the sp orbital of the other carbon. Pi bond formation takes place between the p-orbital of the two carbon atoms. So we shall apply this concept in understanding various triple bond examples.
Triple bond examples
1. Acetylene
It is considered as the most simplest hydrocarbon containing the triple bond CH≡CH, one sigma + two pi bonds. It is a tetravalent compound with valency-4. We know that carbon and hydrogen are involved in the formation of acetylene. So the atomic number of carbon is 6, its valency is four, meaning the number of electrons available for bond formation. This are very common triple bond examples .
Image credit : Wikipedia
Hydrogen with atomic number 1 can share its electron for bond formation. So in the acetylene molecule C2H2, two carbon atoms and two hydrogen atoms combine together.
The type of hybridization associated with acetylene ( ethyne ) is sp, meaning it has half s – character and half p – character, has a bond angle of 180 degrees, and possesses linear geometry. It is observed that the electronic configuration of carbon in the ground state is 1s2 2s2 2px1 2py1, so there are only two electrons that are unpared, but carbons valency is 4.
So for bond formation, it requires 4 electrons. Therefore 2 electrons from s orbitals go to 2pz orbital, which is empty during the excited state. So during the excited state now the carbons electronic configuration becomes 1s2 2s1 2px1 2py1 2pz1.
Every atom of carbon hybridizes by sp hybridization of 2s and 2p orbitals during excited state giving two half-filled orbitals ( sp ) having a liner arrangement.
2. Carbon monoxide :
A triple bond is found between a carbon atom and an oxygen atom. It consists of 1 sigma and 2 pi bonds. It is said that carbon monoxide has the strongest covalent bond. The bond formation between carbon and oxygen takes place by covalent bonding, i.e., sharing of electrons between 2 atoms ( carbon, oxygen ).
Image credit : Wikipedia
When the carbon atom obtains the lone pair from the oxygen electron, the resultant bond is non-covalent. So 2 are covalent bonds, and 1 is non-covalent bond. The bond order is found out to be 3.
The valence electron in carbon is 4 and in oxygen is 6. It becomes much more easier to determine hybridization if we know the steric number of the molecule ( steric number – is said to be the number of pairs of lone pairs around the central atom ). It is observed that the molecules which have 2 as the steric number, the hybridization is said to be sp.
Image credit : Wikipedia
The C-O sigma bond results from 2pz orbital of carbon and 2pz orbital of oxygen overlapping. Out of two pi bonds, one pi bond results from 2px orbital of carbon and 2px orbital of oxygen overlapping, and the second pi bond results from 2py orbital of carbon and 2py orbital of oxygen overlapping.
Read more: SN2 Mechanism
3. Propyne
It is a molecule in which covalent bonding is between 2 carbon atoms. So basically, propyne is made up of 3 atoms of carbon and 4 atoms of hydrogen. The first carbon is bonded to one hydrogen by a single bond and attached to the next carbon by a triple bond. And the second carbon is attached to 1 carbon by triple bond and another carbon by a single bond.
Image credit : Wikipedia
The third carbon bond is attached with 3 hydrogen atoms by a single bond. So, therefore, it has 6 sigma and 2 pi bonds. The melting point of propyne is negative 104 degrees Celsius and the boiling point 23.1 degrees Celsius. It is observed that it is insoluble in H2O but is found to be soluble in chloroform, benzyne, etc.
As we know that there are 3 carbons in the structure of propyne; considering the first carbon, it has two atoms attached to it, one of carbon and the other of hydrogen. So there is no lone pair around the first carbon atom. Hence its hybridization is observed to be sp.
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Taking into account the second carbon, it is attached to 2 carbon atoms on either side, and no lone pair exists. Therefore its hybridization is sp. Now referring to the third carbon atom, it is attached to 4 atoms, out of which three are hydrogen atoms, and one is a carbon atom, and no lone pair is present, so the hybridization of the carbon is sp3.
4. Benzyne
It is an example of an aryne tripe bond. It is a very reactive intermediate. We can consider this as an exception because the second pi bonding is a result of the weak interaction of sp2 orbitals (hybrid), which is in the rings plane.
Image credit : Wikipedia
The formed triple bond is found to be non-linear in nature due to the strain and reactivity (relatively high ) of the 6-membered aromatic ring. It consists of two sigma bonds ( sp-sp ) and one pi bond (p-p ).
Hybridization: It has been observed that the carbons having triple bonds are sp hybridized, and the remaining four carbons bonded, which are single-bonded, are sp2 hybridized. Benzyne are rare kind of triple bond examples.
Read more : SN1 mechanism
5. 2-butyne
Its chemical formula is C4H6 with melting -32 degrees Celsius and melting point 27 degrees Celsius. Its synonym is Dimethylacetylene. There are nine sigma bonds and two pi bonds in the molecule. The first and the fourth carbon have 4 sigma bonds, and hence it is sp3 hybridized.
Image credit : Wikipedia
6. Nitrogen
Its symbol is N, and the atomic number is observed to be 7 and belongs to group 5. It mostly exists in a gaseous state with a melting point of -209.86 degrees Celsius and a boiling point of -195.795 degrees Celsius. The valence electrons in Nitrogen are five, so in order to complete its octet, it needs more than three electrons.
Image credit : Chemistry stack exchange
Therefore it shares its three electrons with one more Nitrogen atom to satisfy the octet rule. In N2, there is one sigma bond and 2 pi bonds. There is one lone pair present on the N atom. The steric factor in Nitrogen is said to be 1 + 1 = 2. The bond angle in N2 is found to be 180 degrees with linear molecular geometry, and its popularity is observed to be non – polar.
The electronic configuration of N2 is 1s2 2s2 2px 2py 2pz, 3 of the 2p orbitals are left empty. So these half-filled 2p orbitals take part in the bonding. So these three half-filled orbitals from each of the Nitrogen overlap along the axis ( internuclear ) for bond formation. Thus the triple bond between the 2 nitrogen atoms is formed. This N2 is very important for organisms. It is also used in various industries for the manufacturing of fertilizers etc.
FAQs
1. Is F2 a triple bond?
No, Fluorine does not have a triple bond.
F2 is said to have a pure covalent bond. The atomic number of fluorine is said to be 9, and the electronic configuration is 1s2 2s2 2px2 2py2 2pz1. So the number of valence electrons is 7. To achieve a complete octet, it needs one more electron.
It combines with one more fluorine atom and completes its octet. Bonding occurs between 2pz of one fluorine atom and 2pz of 2nd fluorine atom, and the resultant is a covalent bond. There are 3 lone pairs of electrons on the F1 atom ( each ).
2. Is H2 a triple bond?
No, H2 does not have a triple bond.
It forms a bond by single bond formation. As we know that its atom is a non-metal, so H2 (molecule) bond formation will be covalent. It is also observed to be a non-polar (covalent) bond as the bond formation takes place between the same atoms, therefore there is no difference in their electronegativity, in other words, what it means is that the atoms of hydrogen and electrons are equally shared.
Its melting point is -259.9 degrees Celsius, and its boiling point is observed at -252.8 degrees Celsius. It is considered the most lightest of all the elements. It is quite stable but still is capable of forming various bonds. It has three isotopes, Tritium, Deuterium, and Protium, and all of the three have variations in their properties.
H2 is found to be inflammable (highly) and can catch fire in the atmosphere if it encounters the required conditions.
If we speak about hybridization, there is no hybridization in hydrogen as it has only one electron, so logically it is not possible to mix the orbitals and form hybrid orbitals.
3. Is HCN a triple bond?
Yes, HCN (hydrogen cyanide) has a triple bond (between carbon and nitrogen atom).
It is found to be hazardous. So while working with, it one must be very careful. It can exist in liquid or gaseous form.
The melting point is -13.29 degrees Celsius and, the boiling point is 26 degrees Celsius. The HC-N molecule has a linear geometry. Hydrogen cyanide is a weak acid; it can ionize partially in the presence of water, resulting in an anion of CN−. Thus hydrocyanic acid is formed. It is used in the mining industry for gold and silver mining.
Also, many important organic compounds are prepared using HCN like EDTA, adiponitrile (it is a precursor for Nylon -6,6.) Hydrogen cyanide consists of three atoms (one hydrogen, one carbon, and one Nitrogen). The bond between carbon and hydrogen is single, while the bond between carbon and Nitrogen is triple. The steric number is found out to be 2.
The hydrogen in this molecule is not having any hybridization as the one hydrogen electron is bonded with one carbon electron, thus satisfying its valency. The hybridization of carbon in the molecule is sp .
Please, click to know about SiCl2Br2 Lewis Structure and Density Of Dichloromethane.
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This is Sania Jakati from Goa. I am an aspiring chemist pursuing my post graduation in organic chemistry. I believe education is the key element that moulds you into a great human being both mentally and physically. I’m glad to be a member of scintillating branch of chemistry and will try my best to contribute whatever I can from my side and Lambdageeks is the best platform where I can share as well as gain knowledge at the same time.
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