Question

Does anyone know what is the oxidation number of the Nitrogen in this compound? CO(NH2)2 and how did you knew it?

Answer 1

Should that be Co and not CO?

Answer 2

@JazRad Co is not an element anywhere on the Periodic Table of Elements. CO, however, is Carbon Monoxide.

@skadood The oxidation number of Nitrogen in this compound is -2. If you look on the Periodic Table of Elements you can find the oxidation number to the right of the atomic symbol. Elements have different oxidation numbers depending on the compound. But, in this case, Nitrogen only has one oxidation number, which is -2.

Answer 3

You probably have urea there:



We can safely assume the oxidation state of the O is -2, and of the Hs +1 each. The total charge on the molecule is zero, so all the oxidation states have to add up to zero. We have -2 + 4(+1) + 2x + y = 0, where x is the oxidation number of each nitrogen and y is the oxidation number of the carbon. That simplifies to 2x + y = -2, which describes a line with slope -2 and intercept -2. Since x and y must be integers, we consider the points on this line that have integer values of x and y. Only consider the pairs near (0,0) because the oxidation numbers will be small. The points on the line closets to (0,0) are: (-3,4), (-2,2), (-1,0), (0,-2), (1,-4). Keep in mind the first number is the oxidation number of the nitrogen, the second of the carbon.

Of that set, the first, -3 for the nitrogen and 4 for the carbon is by far the most likely. Nitrogen is more electronegative than carbon, so it's likely to have the more negative number. Furthermore, 4 is a typical number for carbon double-bonded to oxygen, e.g. in CO2, and carbon is double bonded to oxygen here. -3 is also a typical oxidation number for nitrogen single-bonded to hydrogen, e.g. in NH3, and here nitrogen is single bonded to hydrogen.

Therefore, the oxidation number of nitrogen in this compound is probably best descirbed as -3.

N.B. Co is the chemical symbol for cobalt. But I don't think you mean that.