Dewar–Chatt–Duncanson model facts for kids
The Dewar–Chatt–Duncanson model helps us understand how certain metals and alkenes (a type of molecule) connect. It explains the special chemical bond they form. This model is named after the scientists Michael J. S. Dewar, Joseph Chatt, and L. A. Duncanson.
Contents
How Metals and Alkenes Connect
This model describes a two-way "handshake" of electrons between a metal and an alkene molecule.
Giving Electrons to the Metal
First, the alkene shares some of its electrons with the metal. Imagine the alkene has a cloud of electrons (called a "pi-orbital"). It gives some of these electrons to an empty space (called a "d-orbital") on the metal. This is like the alkene donating a small gift of electrons to the metal.
Getting Electrons Back from the Metal
Second, the metal also shares its electrons back with the alkene. The metal has its own cloud of electrons (in a "filled d-orbital"). It gives some of these electrons to an empty space on the alkene (called a "pi-antibonding orbital"). This is like the metal giving a gift back to the alkene.
What Happens to the Alkene?
When these electrons are shared back and forth, it changes the alkene molecule.
- The bond between the two carbon atoms in the alkene becomes a bit weaker and longer.
- The hydrogen atoms on the alkene also bend away from the metal. This shows that the carbon atoms are changing their shape slightly.
Real-World Examples
Scientists have seen these changes in real chemical compounds.
- In a substance called Zeise's salt, the bond between the two carbon atoms in the ethylene molecule gets a tiny bit longer. It goes from 133 picometres to 134 picometres.
- In another compound with nickel and ethylene, the carbon-carbon bond becomes even longer, reaching 143 picometres.
These examples show that the Dewar–Chatt–Duncanson model helps explain how these interesting chemical connections work!
