To understand the 3D molecular shape of the molecule, we have an interesting theory: VSEPR theory. While Lewis Structure gives us an idea about the internal bond types and valence electron sharing inside a given molecule, it can only explain a two-dimensional geometry. Molecular geometry or molecular shape is an important concept that we need to decipher while we are learning the chemical bonding of any chemical composition. If we indicate single bonds by straight lines, a 2D representation of the Nitrogen Trifluoride molecule will look like this:
Therefore, we have attained our most perfect Lewis Structure diagram. We calculate formal charge via the below-mentioned formula:įormal charge for Nitrogen atom = 5 – 0.5*6 – 2 = 0.įormal charge for each Fluorine atom = 7 – 0.5*2 – 6 = 0.Īs we can see, all the atoms inside the NF3 molecule have the least possible formal charge values. The formal charge can be defined as the electric charge assigned to any given molecular atom assuming that electrons are always shared equally amongst the constituent elements. Our last step towards getting the required structural sketch is the concept of Formal Charge. The above graphical representation of NF3 shows that all the three surrounding Fluorine atoms and the central Nitrogen atom have achieved octet fulfillment. Let us check if we have fulfilled the octet rule in our Lewis structure. Main group elements present in the same period have this tendency to achieve a valency of eight while forming bonds inside a molecule. Noble gases like Neon, Argon, Xenon have eight electrons in their valence shells. The main group (group 1- 17) elements tend to attain the electronic configuration of the outermost shell of noble gas elements. Let us now understand the next important concept of Lewis Structure: We have put the valence dot structures and made a sketch of the NF3 molecule. Let us sketch a probable Lewis Structure for Nitrogen Trifluoride. In Lewis Structure, we denote valence electrons by dot notations. Electropositive atoms, on the other hand, are more prone to share and aid in bond formation. This is because electronegative atoms are usually reluctant to share electrons. Nitrogen is more electropositive than fluorine and we will keep it in the center. The total number of valence electrons in a NF3 molecule = 5 + 7*3 = 26. Nitrogen has 5 and fluorine has seven valence electrons. Nitrogen belongs to group 15 and fluorine, being a halogen, belongs to group 17. The combining or the binding power or capacity is termed as Valency.Īs we can see, the above diagram gives us the Periodic table. The electrons that are present in the outermost shell of an atomic nucleus are known as valence electrons.
In Lewis Structure, we try to find a suitable pictorial representation of a molecule to have an idea of the chemical bonding occurring inside the molecular structure.īefore we proceed, we need to learn about a very important concept: Valence Electrons. Nitrogen trifluoride is a chemical molecule having one atom of nitrogen and three atoms of fluorine.
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