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Bond Angle Comparison Water Ammonia
Analysis of the difference between the bond angles between water and ammonia
Water ($H_2O $) and ammonia ($NH_3 $) are both common compounds, but their bond angles are different. The bond angle of water is about 104.5 dollars ^ {\ circ} $, the bond angle of ammonia is about 107.3 dollars ^ {\ circ} $, and the bond angle of water is smaller than that of ammonia. The reason for this is to analyze the interaction between the molecular structure and the electron pair.
First, the hybridization mode of the central atom. In the water and ammonia molecules, the oxygen atom and the nitrogen atom are both hybridized by $sp ^ 3 $. The hybridization of $sp ^ 3 $forms four $sp ^ 3 $hybrid orbitals, which are distributed in a tetrahedral configuration.
On the influence of lone electron pairs and bonding electron pairs. In ammonia, there are five electrons in the outer layer of the nitrogen atom, three of which form covalent bonds with the hydrogen atom, and there is a pair of lone electron pairs. In water molecules, there are six electrons in the outer layer of the oxygen atom, two electrons form bonds with the hydrogen atom, and the remaining two pairs of lone electron pairs. There is a repulsive force between the lone electron pair and the bonding electron pair, and the repulsive force between the lone electron pair is greater than the repulsive force between the lone electron pair and the bonding electron pair, and the repulsive force between the bonding electron pair is the smallest. Ammonia molecules have a pair of lone electron pairs, water molecules have two pairs of lone electron pairs. The repulsion force between lone electron pairs in water molecules is greater, and the repulsion of bonding electron pairs is more severe, resulting in a smaller angle between bonding electron pairs. Therefore, the bond angle of water is smaller than that of ammonia.
Looking at the electronegativity factor again. The electronegativity of oxygen is greater than that of nitrogen, and the oxygen atom has a stronger ability to attract electrons, so that the $O-H $bond electron cloud is more biased towards oxygen atoms, and the mutual repulsion between bonding electron pairs is relatively weakened. However, the electronegativity of nitrogen atoms is relatively small, and the degree of repulsion between bonding electron pairs in the $N-H $bond electron cloud is weaker than that of the $O-H $bond. The repulsion between bonding electron
In summary, because the number of solitary electron pairs in water molecules is more than that of ammonia molecules, and the electronegativity of oxygen atoms is greater than that of nitrogen atoms, the bond angle of water is smaller than that of ammonia under the combined action. This is the key to explaining the difference between the bond angle of water and ammonia from the molecular structure and the nature of electronic interaction.
Water ($H_2O $) and ammonia ($NH_3 $) are both common compounds, but their bond angles are different. The bond angle of water is about 104.5 dollars ^ {\ circ} $, the bond angle of ammonia is about 107.3 dollars ^ {\ circ} $, and the bond angle of water is smaller than that of ammonia. The reason for this is to analyze the interaction between the molecular structure and the electron pair.
First, the hybridization mode of the central atom. In the water and ammonia molecules, the oxygen atom and the nitrogen atom are both hybridized by $sp ^ 3 $. The hybridization of $sp ^ 3 $forms four $sp ^ 3 $hybrid orbitals, which are distributed in a tetrahedral configuration.
On the influence of lone electron pairs and bonding electron pairs. In ammonia, there are five electrons in the outer layer of the nitrogen atom, three of which form covalent bonds with the hydrogen atom, and there is a pair of lone electron pairs. In water molecules, there are six electrons in the outer layer of the oxygen atom, two electrons form bonds with the hydrogen atom, and the remaining two pairs of lone electron pairs. There is a repulsive force between the lone electron pair and the bonding electron pair, and the repulsive force between the lone electron pair is greater than the repulsive force between the lone electron pair and the bonding electron pair, and the repulsive force between the bonding electron pair is the smallest. Ammonia molecules have a pair of lone electron pairs, water molecules have two pairs of lone electron pairs. The repulsion force between lone electron pairs in water molecules is greater, and the repulsion of bonding electron pairs is more severe, resulting in a smaller angle between bonding electron pairs. Therefore, the bond angle of water is smaller than that of ammonia.
Looking at the electronegativity factor again. The electronegativity of oxygen is greater than that of nitrogen, and the oxygen atom has a stronger ability to attract electrons, so that the $O-H $bond electron cloud is more biased towards oxygen atoms, and the mutual repulsion between bonding electron pairs is relatively weakened. However, the electronegativity of nitrogen atoms is relatively small, and the degree of repulsion between bonding electron pairs in the $N-H $bond electron cloud is weaker than that of the $O-H $bond. The repulsion between bonding electron
In summary, because the number of solitary electron pairs in water molecules is more than that of ammonia molecules, and the electronegativity of oxygen atoms is greater than that of nitrogen atoms, the bond angle of water is smaller than that of ammonia under the combined action. This is the key to explaining the difference between the bond angle of water and ammonia from the molecular structure and the nature of electronic interaction.
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