The charge that an atom in a molecule would develop if the most-electronegative atoms in the molecule took the shared electrons from the less-electronegative atoms is the _______.

Question

A. corrosion factor

B. oxidation number

C. oxidation process

D. reduction process

E. None of the Above

Answer 1

Oxidation and reduction refers to the transfer of electrons between atoms and molecules. Options C and D are referring to an actual process (ie, an oxidation-reduction, or redox, reaction), so those answers are not correct.

A would not be correct because a corrosion factor is anything that influences the rate of corrosion of a given substance.

Your answer would be B. An oxidation number (sometimes called an oxidation state), is positive or negative integer that is assigned to an atom to indicate it’s hypothetical charge if the most electronegative atoms took the shared electrons from the least electronegative atom in a given molecule.

For example, in the compound ferric chloride (FeCl3), we know that chlorine has an oxidation state of -1 (this is because halogens have 7 electrons in their valence shell, if they take another electron to satisfy the octet rule, they will bear a -1 charge). We have 3 chlorine atoms, each of which are going to have a -1 oxidation number. We don’t know the oxidation state of iron, so we can set up an algebraic expression to find this

xX + yY = 0

where X = the number of iron atoms, x = irons oxidation state, Y = number of chlorine atoms, and y = the oxidation state of chlorine.

This equation is set to zero because the sum of the oxidation states of all atoms in a neutral molecule (ie an atom without formal charges) is equal to zero.

Substituting the values into the expression you will get:

x(1) + (-1)(3) = 0

x + -3 = 0

x = +3

The oxidation state of iron tells us that if three chlorine atoms form ironic bonds with it, iron will give up 3 of its electrons to the more electronegative chlorine atoms (1 electron to each Cl atom), which would hypothetically give iron a +3 charge or oxidation number (its positive because when an atom loses electrons, it will have more protons than electrons and is considered to be electron deficient, so it will have a positive charge due to it having an excess of protons). Hence why the name of ferric chloride is written as iron (III) chloride. The Roman numerals indicate iron’s oxidation state.