To describe the characteristics of a molecule of ammonia (NH₃), we need to look at the bond polarities, molecular shape, and overall molecular polarity.
### Step-by-Step Solution
1. Lewis Structure of Ammonia (NH₃):
- Nitrogen (N) atom is the central atom.
- Nitrogen has 5 valence electrons; each hydrogen (H) atom has 1 valence electron.
- Each hydrogen atom forms a single bond with the nitrogen atom, using 3 of nitrogen's valence electrons.
- There will be 2 electrons left on nitrogen, which form a lone pair.
The Lewis structure can be represented as follows:
```
H
|
H - N - H
|
Lone pair of electrons
```
2. Bond Polarities:
- To determine the bond polarities, we refer to the electronegativities of nitrogen and hydrogen.
- Nitrogen has an electronegativity of approximately 3.0.
- Hydrogen has an electronegativity of approximately 2.1.
- Since the electronegativity difference (3.0 - 2.1 = 0.9) is between 0.5 and 1.7, the N-H bonds are polar covalent bonds.
Thus, the bond polarities in ammonia (NH₃) are polar.
3. Molecular Shape:
- To determine the molecular shape, we use the VSEPR (Valence Shell Electron Pair Repulsion) theory.
- NH₃ has three bonded pairs and one lone pair of electrons around the central nitrogen atom.
- According to VSEPR theory, the molecular shape of a molecule with three bonds and one lone pair is trigonal pyramidal.
4. Overall Molecular Polarity:
- Since the N-H bonds are polar and the molecule has a trigonal pyramidal shape, the molecule is not symmetrical.
- The lone pair of electrons on nitrogen creates a region of higher electron density, resulting in an uneven distribution of charge.
- This asymmetry makes the entire ammonia molecule polar.
### Final Answer:
The bond polarities are polar, the molecular shape is trigonal pyramidal, and the molecule is polar.
