Draw the Lewis structure of ammonia (NH₃).
The Correct Answer and Explanation is :
Here’s a breakdown of how to correctly draw the Lewis structure of ammonia and an explanation of its characteristics:
- Identify Valence Electrons: Nitrogen (N) has 5 valence electrons, and each hydrogen (H) atom has 1 valence electron. Therefore, the total number of valence electrons available for NH₃ is ( 5 + 3 \times 1 = 8 ) electrons.
- Draw the Skeleton Structure: Nitrogen, being less electronegative and able to form more bonds, is placed in the center with three hydrogen atoms surrounding it.
- Distribute Electrons: Starting with the hydrogen atoms, each hydrogen atom needs two electrons to complete its valence shell. Three bonds are formed between nitrogen and each hydrogen, using up 6 of the 8 available electrons.
- Complete Octets: After forming three N-H bonds, 2 electrons remain. These are placed as a lone pair on the nitrogen atom. This lone pair is crucial as it influences the molecule’s geometry and reactivity.
- Check the Formal Charges: To ensure the stability of the Lewis structure, check the formal charges. Both nitrogen and hydrogen atoms have formal charges of zero in this structure, which confirms its stability.
- Molecular Geometry: The presence of the lone pair and the three bonded pairs of electrons around nitrogen result in a trigonal pyramidal molecular geometry. This geometry is different from a tetrahedral due to the repulsion caused by the lone pair which slightly compresses the bond angles to about 107 degrees.
- Electronegativity and Polarity: Nitrogen is more electronegative than hydrogen, which makes each N-H bond polar. The overall molecule is also polar due to the asymmetrical distribution of electrons caused by the lone pair on nitrogen.
This explanation covers the essentials of drawing and understanding the Lewis structure of ammonia, including the molecular geometry and the effect of lone pairs on bond angles and polarity.
Let’s create an image that visually represents this explanation for the Lewis structure of ammonia:
Here is the visual representation of the Lewis structure for ammonia (NH₃) as described. The diagram includes the nitrogen atom at the center with its five valence electrons, connected to three hydrogen atoms, each sharing electrons with nitrogen to form three single bonds. The lone pair on the nitrogen is also shown, and the molecular geometry is labeled as trigonal pyramidal. The arrows indicate the polarity of the bonds due to the difference in electronegativity between nitrogen and hydrogen. This should help you confirm and visualize the concepts explained earlier.
