NH4NO3 Lewis Structure & Characteristics (15 Complete Facts)

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NH4NO3 or Ammonium Nitrate is an inorganic salt and an ionic compound. Let us discuss its lewis structure and characteristics in detail.

The Lewis structure of NH4NO3 is formed by two polyatomic ions – NH4+ and NO3–. The central atom in both the ions is Nitrogen. In NH4+, N is attached to each of the four H atoms by a single bond. In NO3–, N is attached to each of the two O atoms by a single bond and one O atom by a double bond.

Let us discuss Lewis structure of NH4NO3 and its characteristics below.

How to Draw NH4NO3 Lewis structure?

To draw lewis structure for NH4NO3, let us follow the below steps separately for NH4+ and NO3–.

Step 1: Find the total valence electrons of cation and anion

In NH4+ ion, N and H atoms have 5 and 1 valence electrons respectively. Thus, the total electrons for NH4+ = 5+4*1-1= 8. For NO3– ion, Nitrogen and oxygen has 5 and 6 valence electrons respectively. Thus, the total valence electrons of NO3– = 5+3*6+1 = 24

Step 2: Find the least electronegative central atom

The central atom in both NH4+ and NO3– is Nitrogen. In NH4+ ion, H instead of being least electronegative is not the central atom because it cannot form multiple bonds.

Step 3: Make single bonds between N and the outer atoms

In NH4+, all 8 electrons are used in forming 4 single bonds with the hydrogen atoms. In NO3–, Only 6 electrons out of 24 are used for bonding.

Step 4: Put the left electrons as lone pairs or make bond

In NH4+, all the H atoms have completed their duplet. In NO3–, we have 18 valence electrons remaining that can complete octet of the outer O atoms. But the octet of N is still incomplete. Move one lone pair from one O atom to complete the octet of N.

Step 5: Determine the formal charge

In the Lewis structure of NH4NO3, formal charge NH4+ is +1 and NO3– is -1. So, the net formal charge on the molecule is zero.

             

nh4no3 lewis structure
Lewis structure NH4NO3

NH4NO3 Lewis structure shape

The molecular geometry is decided both by bond pairs and the lone pairs while electron geometry is decided by the bond pairs alone. Let us discuss the shape of NH4NO3.

Molecular geometry as well as the electron geometry of NH4+ is tetrahedral. For NO3– ion, molecular geometry as well as electron geometry is trigonal planar.

NH4NO3 Lewis structure formal charge

Formal charge helps us to check the stability of the Lewis structure. Let us discuss formal charge of NH4NO3.

The formal charge on the Lewis structure of NH4NO3 is 0. The formal charge of NH4+ and NO3– ions is +1 and -1 respectively. One positive and one negative charge gets neutralized and net formal charge is zero.

The formal charge on each atom in NH4+ and NO3– is as follows-

 In NH4+ ion:

  • On central atom N = 5 – 0.5*8 – 0 = +1
  • On each of four H atoms = 1- 0.5*2 – 0 = 0
  • So net formal charge on NH4+ = +1

In NO3– ion:

  • On central N atom = 5 – 0.5*8 – 0 = +1
  • On each of two single bonded O atom = 6 – 0.5*2 – 6 = -1
  • On double bonded O atom = 6 – 0.5*4 – 4 = 0
  • So net formal charge on NO3– = -1

NH4NO3 Lewis structure angle

Bond angle is affected by the presence of lone pairs on central atom. Let us explore the bond angle of NH4NO3.

The bond angle of NH4+ ion is 109.5 degrees as it has a tetrahedral shape and no lone pair is present on the central N atom. Whereas, NO3– ion has a bond angle of 120 degrees as it has trigonal planar geometry and no lone pairs are found on central N atom.

NH4NO3 Lewis structure octet rule

Atoms try to achieve electronic configuration of eight valence electrons like the noble gases. Let us discuss the octet rule for NH4NO3.

In NH4NO3, N and O atoms have complete octet of electrons. Hydrogen does not follow octet rule so it completes its duplet by forming single bond with central atom N. By completing their duplet, H atoms achieve the noble gas configuration of Helium.

NH4NO3 Lewis structure lone pairs

Lone pairs are the unshared electron pairs found in the last shell. Let us discuss the lone pairs of NH4NO3.

In NH4NO3, there are 8 lone pairs. In NO3– , there are three lone pairs on each of the two single bonded Oxygen atom and 2 lone pairs on the double bonded O atom.

Distribution of lone pairs in NH4NO3 are as follows –

  • On the double bonded O atom = 2 lone pairs
  • On each of the two single bonded O atoms = 3 lone pairs
  • Thus, total lone pairs in NH4NO3 = 2+3*2 = 8 lone pairs

NH4NO3 valence electrons

Valence electrons decide the combining capacity of an element. Let us discuss the valence electrons of NH4NO3.

There is a total of 32 valence electrons in the NH4NO3 Lewis structure. The valence electrons in the outer shell of N, O and H atoms are 5, 6 and 1 respectively.

The valence electrons in the NH4NO3 structure are as follows –

In NH4+

  • in N = 5
  • In H = 1
  • For positive charge on NH4+ ion (loss in one valence electron) subtract one.
  • Thus, total valence electron for NH4+= 5+4*1-1 = 8

In NO3–

  • In N = 5
  • In O atom = 6
  • For negative charge on NO3– ions (gain in one valence electron) add one.
  • Thus, total valence electrons for NO3– = 5+3*6+1 = 24
  • Total valence electrons for NH4NO3 = 24+8 = 32

NH4NO3 hybridization

Hybridization is the merging of atomic orbitals of the same atom. Let us discuss the hybridization of the central atom N of NH4NO3.

The N atom in NH4+ is sp3 hybridized because it is bonded to each of the four H atoms by a single bond and has no lone pairs on it. In NO3– ion, N is sp2 hybridized as it is bonded to each of the two O atoms by a single bond and one O atom by a double bond. It has no lone pairs present on it.

NH4NO3 solubility

Solubility means the dissolving ability of a solute in a given solvent. Let us discuss the solubility of NH4NO3.

NH4NO3 is readily soluble in water but insoluble in ethers. It sparingly dissolves in the organic solvents but can be readily solubilised by the addition of crown ether or polyethylene glycol. NH4NO3 is soluble in the following solvents.

  • Water
  • Ethanol
  • Acetone
  • Alkalies
  • Methanol
  • Ammonia

Is NH4NO3 solid or liquid?

Substances exists in any of the three states: solid, liquid and gas. Let us find out the state of NH4NO3.

NH4NO3 exists as a colorless crystalline solid with a melting point of 442.8K. It consists of NH4+ and NO3– ions. Because of strong forces of attraction between these ions, NH4NO3 exists in the solid state.

Is NH4NO3 polar or non-polar?

Polarity of a molecule is affected by the electronegativity, dipole moment and molecular geometry. Let us discuss for NH4NO3.

NH4+ ion is non-polar because of the symmetry of the ion and its net dipole moment is zero. NO3– ion is polar because charge distribution around it is not uniform.

Is NH4NO3 acidic or basic?

The salts are formed by the reaction between an acid and a base. They can be acidic, basic or neutral. Let us discuss the nature of NH4NO3.

NH4NO3 is acidic salt because it is formed by the reaction between a strong acid (HNO3) and a weak base (NH3). The reaction can be represented as, NH3 + HNO3 = NH4NO3.

Is NH4NO3 electrolyte?

Electrolytes can be an acid, a base or a salt. They form ions when stirred in water. Let us find out whether NH4NO3 is an electrolyte or not.

NH4NO3 is an electrolyte as it forms ions when dissolved in water. NH4+ and NO3– ions so formed can conduct electricity.

Is NH4NO3 ionic or covalent?

Ionic compounds have electrostatic force of attraction between constituent ions while covalent compounds do not. Let us explore about NH4NO3.

NH4NO3 is an ionic compound because it is formed by the electrostatic attraction between NH4+ and NO3– ions.

Is NH4NO3 tetrahedral?

The shape of the compound is decided by the hybridization of the central atom and number of lone pairs present on it. Let us know about NH4NO3.

The central atom NH4+ is sp3 hybridized so it has tetrahedral geometry. In NO3– ion, the central atom N is sp2 hybridized so it has trigonal planar geometry.

Conclusion

To summarize, NH4NO3 is an ionic compound. It consists of two ions – NH4+ and NO3– ions. NH4+ ion has tetrahedral geometry while NO3– ions has a trigonal planar geometry.

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