Do you know what is present in the maximum amount of fish excrement? Ammonia! Yes, you read it right.
Ammonia (NH3) is composed of nitrogen and hydrogen and has the chemical formula NH3. It is a colorless gas. It has a particularly pungent smell. It is present in small quantities in air and soil. It is formed by the decay of nitrogenous organic matter like urea.
Usually found in plants and algae living in water bodies such as lakes and streams. It can be toxic to humans in minute quantities.
Ammonia is referred to as a binary compound, meaning that it was formed from two non-equivalent types of atoms.
It is also the simplest binary pnictogen hydride. NH3 boils at −33.34 °C (−28.012 °F) at standard pressure. It must be stored under pressure or at a low temperature.
Let us explore if ammonia is a covalent or ionic compound in this article!
So, is NH3 ionic or covalent? Ammonia is a covalent compound because of the electronegativity difference between hydrogen and nitrogen atom ie; 0.9. Nitrogen and hydrogen atoms share their electrons with each other to form a single covalent bond resulting in the formation of a covalent NH3 compound.
Nonmetals such as nitrogen and hydrogen atoms when combined are in their natural state.
The compound doesn’t have any tendency of either accepting or donating electrons, or tend to share their valence. Thus, it makes ammonia a covalent compound.
Why is Ammonia a covalent compound?
Ammonia is covalent due to the electronegativity difference between nitrogen and hydrogen. The atomic number of nitrogen is 7 while the atomic number of hydrogen is 1.
If we dig deep into the electronic configuration of nitrogen and hydrogen separately we will find that nitrogen has two electrons in the first shell and 5 electrons in the second shell.
Hydrogen only has one electron in the first shell in total. If nitrogen has to become inert then it must have three more electrons in the second shell.
Three hydrogens in total are required to stabilize a nitrogen atom. Whereas all three hydrogens need one electron each to be stable.
With this calculation, we can see as nitrogen does have the space to fit three more electrons and it could easily share its electrons with three hydrogen atoms.
Therefore three hydrogen atoms will react with a single nitrogen atom to mutually share electrons and to become completely inert.
This kind of reaction makes a compound covalent.
We can also justify the covalent nature of ammonia by applying Fajan’s rule. In NH3, the positive ion is the hydrogen cation (H+) and, the negative ion is nitrogen (N-).
The anion (-ve ion) is significantly larger than the cation (+ve ion). It implies that the covalent nature of the ammonia compound is due to Fajan’s rule.
What is a Covalent Compound?
Covalent compound ― when two non-metallic elements share electrons to form a stable compound. These compounds share an equal number of electrons to become inert. Bonds present in such compounds are called covalent bonds.
These bonds could be categorized into three categories:
1. Single covalent bond
2. Double covalent bond
3. Triple covalent
Single covalent bonds do share only one electron mutually with another atom. Ammonia is a prime example of exhibiting single covalent bonds.
Double covalent bonds share two electrons mutually with another atom to complete the valence. Example: atmospheric oxygen (O2).
Triple covalent bonds have three or more electrons shared mutually between two atoms to form an inert compound. Example: N2.
You can refer to the covalent bonds in O2.
Conditions for the formation of a covalent compound
1. Both atoms should have high ionization potential
2. Both atoms should have a high electron affinity
3. The electronegativity difference should be zero or negligible
Polar and Nonpolar Covalent Compounds
The covalent compounds are said to be polar when the shared pair of electrons is not equal in distance between the two atoms.
This happens when the electronegativity of one atom is higher than the other, it tends to pull the electrons with less electronegativity on its side.
This situation creates a slight negative charge on the atom with higher electronegativity and a slight positive charge on the other atom. In this case, a compound is termed a polar covalent compound.
For example Hydrogen Fluoride, ammonia, water.
The covalent compounds are said to be nonpolar when the shared pair of electrons are at an equal distance between the two atoms. This happens when the electronegativity of both atoms is equal.
These kinds of covalent compounds equally share their electrons and are known as nonpolar covalent compounds. For example H2, O2, N3.
Check out the article on the polarity of H2.
Properties of Covalent Compounds
1. They can exist as solid, liquid, or gases at standard room temperature and pressure.
2. Low melting and boiling points
3. Soluble in organic liquids and insoluble in water
4. Poor electricity conductor
What are Ionic Compounds?
Ionic compounds are formed when a metallic element reacts with a non-metallic element. Metal donates electrons and nonmetals accept electrons.
Ionic compounds and electrovalent compounds are the same. Example: NaCl, MgCl2.
Properties of ionic compounds
1. These are solid, hard but brittle.
2. Good conductor of electricity in a molten state
3. High melting and boiling point
4. Soluble in water but insoluble in organic solvents
Properties of Ammonia
1. Ammonia dissociates into its primary elements, i.e; nitrogen and hydrogen when heated.
2. The reaction of water and ammonia gives ammonium hydroxide.
3. Ammonia forms the corresponding salt when it reacts with an acid.
4. Ammonia does not burn in the air and does not support combustion.
5. Ammonia gives water and nitric oxide, and then finally nitrogen dioxide when it undergoes catalytic oxidation.
6. Ammonia gives dense white fumes when reacted with hydrochloric acid.
1. It is a colorless gas.
2. It has a pungent odor.
3. It has a vapor density of 8.5 that is lighter than the density of air. Therefore, the downward displacement technique is used to collect ammonia from the air.
4. It is basic in nature.
5. Highly soluble in water.
6. Turn red litmus into the blue.
Structure of Ammonia
VSEPR theory predicts the shape of ammonia as a trigonal pyramid. It has an experimentally ascertained bond angle of 106.7°.
The central nitrogen atom, which has five outer valence electrons, gains an additional electron from each hydrogen atom, for a total of eight electrons.
These eight electrons form three electron pairs, which are arranged tetrahedrally.
The ammonia molecule flips itself upside down at room temperature. A relatable analogy is an umbrella turning itself inside out in a powerful wind.
Uses of Ammonia
1. It is used as a refrigerant cooling agent because it evaporates rapidly and produces cooling. These are called chlorofluorocarbons.
2. Explosives production requires ammonia.
3. Ammonia could be utilized as a cleansing agent.
4. It is a major constituent of fertilizers.
Ammonia is a covalent molecule because it has a strong distribution of electrons. It constitutes hydrogen and nitrogen. Each hydrogen atom is missing one electron to become inert like helium. Nitrogen is three electrons short to have a full outer shell. So each hydrogen atom shares its electrons with the three outer electrons of nitrogen.
The nitrogen in ammonia is the central atom and, the hydrogen atoms are the atoms that are attached to the central atom. In the nitrogen atom, there are three valence electrons and in the hydrogen atom, there is one valence electron.
A molecule of ammonia (NH 3 ) is held together by the strong N–H single bonds that form when a hydrogen atom shares an electron with a nitrogen atom. Thus, all four atoms effectively have complete outer shells.