Ammonia (NH3) Lewis Structure | Steps of Drawing
In the lewis structure of ammonia (NH3), there are three N-H bonds and one lone pair on nitrogen atom. Lewis structure of NH3 can be drawn by starting from valence electrons of nitrogen and hydrogen atoms in several steps. Each step of drawing the lewis structure of NH3 is explained in detail in this tutorial. After drawing the lewis structure of NH3, you can decide shape of the NH3 molecule.
NH3 lewis structure
In the lewis structure of NH3, there are three N-H bonds and one lone pair on nitrogen atom. There are no lone pairs on hydrogen atoms which cannot keep more than two electrons.
Steps of drawing lewis structure of NH3
You have to follow several steps to draw the lewis structure of NH3. But, because ammonia is a simple molecule, these steps are not complex and do not require all steps which are used to draw lewis structures of complex molecules and ions. Those steps are explained in detail in this tutorial.
- Find total number of electrons of the valance shells of hydrogen atoms and nitrogen atom
- Total electrons pairs as lone pairs and bonds
- Center atom selection
- Mark lone pairs on atoms
- Mark charges on atoms if there are charges on atoms.
- Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.
Important: Drawing the correct lewis structure is important to draw resonance structures correctly.
Total number of electrons of the valance shells of NH3
There are two elements in NH3; hydrogen and nitrogen. Hydrogen is a group IA element and has only one electron in its last shell (valence shell). Nitrogen is a group VA element in the periodic table and contains five electrons in its last shell. Now we know how many electrons are includes in valence shells of hydrogen and nitrogen atoms.
To find out total valence electrons given by a particular element, you should multiply number of electrons of the valance shell by the number of atoms of that element.
- valence electrons given by hydrogen atoms = 1 * 3 = 3
- valence electrons given by nitrogen atom = 5*1 = 5
- Total valence electrons = 3 + 5 = 8
Total valence electrons pairs
Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells
Total electron pairs are determined by dividing the number total valence electrons by two. For, NH3S, Total pairs of electrons are 4.
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Center atom of NH3 molecule
To be the center atom, ability of having greater valance is important. Then, from hydrogen and nitrogen atoms, which atom has the highest valence? Maximum valence of nitrogen is five. Hydrogen's only valence is one. Therefore, nitrogen atom should be the center atom of NH3. Now, we can draw the sketch of NH3 to describe how atoms are attached with bonds in the molecule.
Lone pairs on atoms
After determining the center atom and sketch of NH3 molecule, we can start to mark lone pairs on atoms. Remember that, there are total of four electron pairs.
- There are already three N-H bonds in the above drawn sketch. Now only one (4-3) electron pair remains to mark on atoms.
- Usually, those remaining electron pairs should be started to mark on outside atoms. But in NH3, hydrogen atom are the outside atoms which cannot keep more than two electron in its last shell. There are already two electrons in hydrogen atoms. Therefore, we cannot mark that electrons pair on hydrogen atoms.
- Therefore, then mark that electron pair on center atom; nitrogen.
Mark charges on atoms
There are no charges on nitrogen atom and hydrogen atoms. Also, remember that NH3 is a molecule which does not have a overall charge.
Check the stability and minimize charges on atoms by converting lone pairs to bonds
Because there is no charges on atoms, no need to reduce charges as a step of obtaining the best lewis structure. Already, we have got the best lewis structure for NH3.
Questions
how many lone pairs of electrons are in the lewis structure for ammonia NH3
in the lewis structure for NH3, there is only one lone pair on nitrogen atom.
Can I say, NH3 is basic by looking the NH3 lewis structure?
NH3 has basic and acidic characteristics. To show basic characteristics, there should be lone pairs to negative charges on molecules or ions. Because there is a lone pair on nitrogen atom, there should be basic properties. As well as, hydrogen atoms are charged positively due to nitrogen's electronegativity, acidic properties exist too.