Question

Lewis structure Number Hectro geometry Number Electron Groups Bonding Groups Molecular of Lone geometry Pairs of Electrons Polar Nomor

Answer 1

Molecule	Lewis Structure	Number of Electron Groups	Electron Geometry	Number of Bonding Groups	Number of Lone Pairs of Electrons	Molecular Geometry	Polar or Nonpolar
NH4+	+ H NH Ammonium ion	4	Tetrahedral	4	0	Tetrahedral	Non-polar
NH3	HINH Ammonia	4	Tetrahedral	3	1	Trigonal Pyramidal	Polar
PI3	Phosphorus trijodide	4	Tetrahedral	3	1	Trigonal Pyramidal	Polar

Drawing Lewis Structure:

Step 1: Consider only valence electrons to draw the lewis structure.

Step 2: Draw a bond between two atoms using two-electron (covalent bond).

Electron groups are nothing but the number of bond pairs, lone pairs, single unpaired electron present in a central atom.

Based on the Valence shell electron pair repulsion theory (VSEPR) Theory, electron-group geometry, and molecular geometry are determined by the number of electron groups and number of bond pairs and lone pairs

Number of electron groups	Electron geometry	Number of Bond Pairs	Number of Lone Pairs	Molecular Geometry
2	Linear	2	-	Linear
3	Trigonal Planar	3	-	Trigonal Planar
3	Trigonal Planar	2	1	Bent
4	Tetrahedral	4	-	Tetrahedral
4	Tetrahedral	3	1	Trigonal Planar
4	Tetrahedral	2	2	Bent

The polarity of the molecule is determined using the bond dipoles.

Explanation:

1. NH₄⁺

Valence electron of Nitrogen = 5

Valence electron of Hydrogen = 1

Nitrogen uses 3 valence electrons to form three covalent bonds with the three hydrogen atoms and using lone pairs nitrogen form co-ordinate bond with other hydrogen atoms.

Lewis structure of Ammonium ion:

+ I Ammonium ion

Ammonium ion . I-Z-I

There are four electron groups (4 Bond Pairs + 0 lone pair) in ammonium ion. So, Electron-group geometry is tetrahedral. It does not have lone pairs, the molecular geometry of ammonium ion is tetrahedral.

The dipole moments of the N-H polar bonds are equal and opposite to each other and cancel each other. So, it is a non-polar molecule. (Nitrogen is more electronegative than hydrogen)

K

Structure of Ammonium ion:

NH4+

2. NH₃

Valence electron of Nitrogen = 5

Valence electron of Hydrogen = 1

Nitrogen uses 3 valence electrons to form three covalent bonds with the three hydrogen atoms leaving one lone pair.

Lewis structure of Ammonia:

H-N-H ammonia

HINH Ammonia

There are four electron groups (3 Bond Pairs + 1 lone pair)in ammonia. So, Electron-group geometry is tetrahedral. It has one lone pair, the molecular geometry of ammonia is trigonal pyramidal.

Nitrogen is more electronegative than hydrogen, bond dipoles pass in the same direction. So, it is a polar molecule.

Structure of Ammonia:

NH3

3. PI₃

Valence electron of Phosphorus = 5

Valence electron of Iodine = 7

Phosphorus uses 3 valence electrons to form three covalent bonds with the three iodine atoms leaving one lone pair.

Lewis structure of PI₃:

:|: Phosphorus triiodide Phosphorus triiodide

There are four electron groups (3 Bond Pairs + 1 lone pair)in PI₃. So, Electron-group geometry is tetrahedral. It has one lone pair, the molecular geometry of PI₃ is trigonal pyramidal. But Iodine too has three lone pairs each and a total 10 lone pairs present in a molecule.

Iodine is more electronegative than phosphorus, bond dipoles do not completely cancel out. So, it is a polar molecule.

Structure of PI₃:

Pla