When it comes to the chemistry of organic compounds, one of the most fundamental concepts is the double bond in ethene. Since it’s one of the simplest organic compounds, it serves as a great example to study how different properties like light, temperature, and pressure affect the chemical bond between carbon atoms. In this article, we’re going to explore a curious phenomenon related to ethene and light absorption.
The Energy of the Double Bond
As mentioned in the question detail, the c=c double bond has a bonding energy of around 614 kJ/mol, which is equivalent to 6.4 eV. To put it in perspective, this energy is strong enough to hold two carbon atoms together, but not too strong to make the compound unstable. In fact, ethene is a stable compound that we can find in many industrial and natural environments.
However, when we look at the absorption spectrum of ethene, we notice that it absorbs light at around 171 nm, which corresponds to an energy of roughly 7.3 eV. This is curious because it implies that ethene can absorb energy that is higher than its bonding energy, which should lead to a complete disintegration of the double bond. But why does it not happen?
The Role of Molecular Orbitals
The answer to this question lies in the molecular orbitals of ethene. Without going into too much detail, a molecular orbital is a mathematical function that describes the probability of electrons being present in a specific region around the atoms that form a molecule. In the case of ethene, the two carbon atoms share three molecular orbitals: one sigma bond and two pi bonds.
When a double bond is excited by light, what happens is that the electrons occupying the pi orbitals get promoted to higher energy levels. This leads to a temporary weakening of the double bond, but not a complete disintegration. The reason for this is that the electrons don’t disappear or fly away, but instead redistribute themselves in different orbitals. In other words, the energy absorbed by the double bond goes towards exciting the electrons, not breaking the bond.
Resonance and Stability
Another concept that plays a role in the stability of ethene is resonance. Resonance is the ability of a molecule to have more than one way of distributing electrons in its orbitals, which creates a kind of stability “buffer” against reactive elements. In the case of ethene, the double bond is able to “resonate” between the two pi bonds, which makes the compound overall more stable.
So to recap, the reason why ethene doesn’t disintegrate upon excitation is that the energy absorbed by the double bond gets distributed among the pi electrons, which promotes them to higher energy levels without breaking the bond. Additionally, the resonance effect of ethene creates a stable foundation for the molecule, which prevents it from reacting too quickly with other elements.
Conclusion
In conclusion, the study of ethene and other organic compounds can help us understand the fundamental principles of chemistry and the interactions between light and matter. While the question of why ethene doesn’t disintegrate upon excitation might seem puzzling at first, a closer look at the molecular orbitals and resonance effects of the compound gives us a clear answer. As always in science, the more we know, the more questions we have to ask.
Why Does Ethene Not Disintegrate Upon Excitation?
When it comes to the chemistry of organic compounds, one of the most fundamental concepts is the double bond in ethene. Since it’s one of the simplest organic compounds, it serves as a great example to study how different properties like light, temperature, and pressure affect the chemical bond between carbon atoms. In this article, we’re going to explore a curious phenomenon related to ethene and light absorption.
The Energy of the Double Bond
As mentioned in the question detail, the c=c double bond has a bonding energy of around 614 kJ/mol, which is equivalent to 6.4 eV. To put it in perspective, this energy is strong enough to hold two carbon atoms together, but not too strong to make the compound unstable. In fact, ethene is a stable compound that we can find in many industrial and natural environments.
However, when we look at the absorption spectrum of ethene, we notice that it absorbs light at around 171 nm, which corresponds to an energy of roughly 7.3 eV. This is curious because it implies that ethene can absorb energy that is higher than its bonding energy, which should lead to a complete disintegration of the double bond. But why does it not happen?
The Role of Molecular Orbitals
The answer to this question lies in the molecular orbitals of ethene. Without going into too much detail, a molecular orbital is a mathematical function that describes the probability of electrons being present in a specific region around the atoms that form a molecule. In the case of ethene, the two carbon atoms share three molecular orbitals: one sigma bond and two pi bonds.
When a double bond is excited by light, what happens is that the electrons occupying the pi orbitals get promoted to higher energy levels. This leads to a temporary weakening of the double bond, but not a complete disintegration. The reason for this is that the electrons don’t disappear or fly away, but instead redistribute themselves in different orbitals. In other words, the energy absorbed by the double bond goes towards exciting the electrons, not breaking the bond.
Resonance and Stability
Another concept that plays a role in the stability of ethene is resonance. Resonance is the ability of a molecule to have more than one way of distributing electrons in its orbitals, which creates a kind of stability “buffer” against reactive elements. In the case of ethene, the double bond is able to “resonate” between the two pi bonds, which makes the compound overall more stable.
So to recap, the reason why ethene doesn’t disintegrate upon excitation is that the energy absorbed by the double bond gets distributed among the pi electrons, which promotes them to higher energy levels without breaking the bond. Additionally, the resonance effect of ethene creates a stable foundation for the molecule, which prevents it from reacting too quickly with other elements.
Conclusion
In conclusion, the study of ethene and other organic compounds can help us understand the fundamental principles of chemistry and the interactions between light and matter. While the question of why ethene doesn’t disintegrate upon excitation might seem puzzling at first, a closer look at the molecular orbitals and resonance effects of the compound gives us a clear answer. As always in science, the more we know, the more questions we have to ask.