Question

The oxidation state of Nitrogen in the Ammonia molecule is -3.
a.) True
b.) False

Answer 1

Hint: The sum of the oxidation numbers is the charge on the ion or molecule and since the ammonia molecule is neutral, therefore the sum of oxidation numbers should be equal to 0. Remember this while trying to solve this question.
Complete answer:
Let us first try and understand what the oxidation state of an element in a compound really is before moving on to try and find the answer to this specific question.
An oxidation state is a number that is assigned to an element in a chemical combination. This number represents the number of electrons that an atom can gain, lose, or share when chemically bonding with an atom of another element. The terms “oxidation state” and “oxidation number” are often used interchangeably.
The transfer of electrons is described by the oxidation state of the molecule. One might mistake formal charge for oxidation state but they are different. Oxidation state is commonly used to determine the changes in redox reactions and is numerically similar to valence electrons, but different from formal charge. Formal charge determines the arrangement of atoms and the likelihood of the molecule existing.
With this in mind, let us try and calculate the oxidation state of Nitrogen in the Ammonia molecule.
We know that ammonia is a neutral compound. Oxidation number of hydrogen is +1 So three hydrogen atoms= 1×3= 3.
Let us take the oxidation state of nitrogen as X.
 So, X + 3 = 0.
 Hence X = -3.
Thus, we can conclude that the oxidation state of nitrogen is -3 in ammonia.
Note:
Remember that you can’t speak about the oxygen state of ammonia. All you can ask is the oxidation state of any one of the elements in the compound. Because you can’t say that oxidation states exist for molecules.