Chapitre 9
Liaisons chimiques : concepts de base
Types de liaisons chimiques
Chemical bonding theories were pioneered by American chemist Gilbert N. Lewis. He developed a model called the Lewis model to explain the type and ...
Symboles de Lewis et la règle de l'octet
Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...
Liaison ionique et transfert d'électrons
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...
Le cycle de Born-Haber
Lattice Energy
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...
Tendances de l'énergie du réseau : taille et charge des ions
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...
Liaisons covalentes et structures de Lewis
Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...
Électronégativité
Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.
Electronegativity values of ...
Polarité de liaison, moment dipolaire et nature de la liaison
Bond Polarity
The absolute value of the difference in electronegativity (ΔEN) of two bonded atoms provides a rough measure of the polarity to be ...
Structures de Lewis des composés moléculaires et des ions polyatomiques
To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:
Determine the ...
Mésomérie
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...
Charge formelle
In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...
Exceptions à la règle de l'octet
Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:
...
Énergies de liaison et longueurs de liaison
Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...
Liaisons des métaux
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the ...
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