Nitrate is an important source of nitrogen and oxygen. It is used as fertilizers (like ammonium, sodium, potassium) in agricultural farms for higher solubility and biodegradability. It also treats heart pains. Both nitrogen and oxygen are important to an ecosystem that includes flora and fauna. NO3 is easily soluble water but too much concentration in drinking water is harmful to human health that affects blood carrying oxygen. In 1916, American chemist, Gilbert N. Lewis introduced the concept of electron dot structure. Below are some rules to frame any compound’s Lewis dot structure.
Construction of NO3 Lewis Dot Structure
Construction of NO3 Lewis Dot Structure
bond pairs – 3 pairs (6 electrons) lone pairs – 9 pairs (18 electrons)
What is a formal charge?
What is a formal charge?
Somewhere, every atom has a formal charge on it. Formal charge plays an important role in Lewis dot structure. It keeps a trace of the electrons assuming they are equally shared between the atoms of the molecule. It does not take care of the atom’s electronegativity but reflects the electron count. If the atom has obtained the electron it will be a negative charge and if the atom loses the electrons, it will be a positive charge. A mathematical formula, a diagram, and the instinctive method are three different ways to calculate the formal charge.
The formal charge of NO3
To find out the formal charge of an individual atom mathematically, the formula will be The formal charge (F.C) = (No. of valence electrons) – (No. of non-bonding pairs electrons) – (No. of bonding pair electrons / 2) F.C of oxygen making a double bond with the nitrogen atom F.C = 6 – 4 – (4/2) = 0 i.e. this atom does not have any formal charge on it. F.C of a nitrogen atom F.C = 5 – 0 – (8/2) = +1 i.e. nitrogen has positive formal charge. F.C of oxygen making single bond with the nitrogen atom F.C = 6 – 6 – (2/2) = -1 i.e. both the oxygen atoms making a single bond with nitrogen have a negative formal charge. To calculate the total charge of the nitrate ion, a pair of +ve and –ve formal charges get canceled and there is only one –ve formal charge left on the oxygen atom. Hence, the ion has a negative formal charge.
Hybridization of NO3
Hybridization of NO3
Hybridization is a process to find the number of atoms attached to the central and lone pair of the atom. It studies the process of how atoms within molecules are oriented in three different dimensions. The most important thing in hybridization is to find out the molecular configuration of a molecule that takes place in the form of a (σ) bond and a pi (π) bond. The very first bond is always a sigma bond and then the second or third bond in the dot structure is a pi bond. The VSEPR theory says about the arrangement in accordance to find out the number of bond pairs through calculating the number of sigma (σ) bonds and lone pair of central atom i.e. steric number that is the number of regions of electron density surrounding the atom. Since the steric number is 3 meaning there are 3 single sigma bonds with zero lone pair resulting in sp2 hybridization. The structure itself depicts that three sp2 orbitals of nitrogen overlap with 1s orbital of the oxygen. The 2p orbitals of oxygen accommodate into a lone pair. Nitrogen’s p orbital makes a bond with three terminal oxygen atoms.
Molecular Geometry of NO3
Molecular Geometry of NO3
As per VSEPR theory, you conclude that NO3 is sp2 hybridized. The model also states that the molecular geometry of the compound is trigonal planar with each orbital equidistant at 120 degrees (bond angle) shaped on a planar region. The formula AX(n) N says that A is the central atom, X is the atom attached to the central atom, (n) is the number of atoms bonded, and N is the number of nonbonding electron pairs. Ignoring N at the moment as there is no lone pair of electrons, the formula becomes AX (3). Hence, the formula directs to the shape of the trigonal planar. The trigonal planar shape of the NO3 molecule creates symmetry across the bonds NO bonds and as a result, the three dipoles created by NO bonds get canceled by each other, and the overall dipole of NO3 is zero. Therefore, the NO3 is a non-polar molecule.
