In order to find the number of unshared electrons present on N atom in Ammonia (NH₃), we will first draw the lewis structure of Ammonia.
Step 1: Calculate number of Total valence Electrons:
# of Valence e⁻s in N = 5
# of Valence e⁻s in H₁ = 1
# of Valence e⁻s in H₂ = 1
# of Valence e⁻s in H₃ = 1
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Total Valence e⁻s = 8
Step 2: Start drawing the structure:
Draw Central atom (N) in center surrounded by three H atoms. Connect N with each H atom through single bond and subtract e elctrons from total valence electrons for each single bon. Therefore, for three single bonds, 6 electrons are subtracted. i.e.
= 8 - 6
= 2
These two electrons left are added to N atom as a lone pair of electron.
Result:
Nitrogen atom in Ammonia possess 2 (two) unshared electrons marked as red in given picture.