Which of the following sequence is correct with reference to the oxidation number of iodine? (a) \(\mathrm{HI}<\mathrm{I}_{2}<\mathrm{ICl}<\mathrm{HIO}_{4}\) (b) \(\mathrm{I}_{2}<\mathrm{HI}<\mathrm{ICl}<\mathrm{HIO}_{4}\) (c) \(\mathrm{HIO}_{4}<\mathrm{ICl}<\mathrm{I}_{2}<\mathrm{HI}\) (d) \(\mathrm{I}_{2}<\mathrm{ICl}<\mathrm{HI}<\mathrm{HIO}_{4}\)

Understanding the oxidation states of elements, such as iodine, is essential in chemistry because it helps explain the substance's ability to gain or lose electrons. Iodine, like other elements, can have multiple oxidation states depending on its chemical environment.

In simple terms, the oxidation state tells us about the hypothetical charge that an atom would have if all bonds to atoms of different elements were completely ionic. For instance, in hydriodic acid (HI), iodine has an oxidation state of -1 due to its bonding with hydrogen, which is less electronegative. However, in the molecular form, iodine (I₂), it has an oxidation state of 0 because the electrons are shared equally between the two iodine atoms.

When iodine pairs with a more electronegative element like chlorine in iodine monochloride (ICl), it takes on a positive oxidation state, +1, to balance chlorine's -1. The most extensive oxidation state of iodine is observed in periodic acid (HIO₄), where it reaches +7 to account for the electrons drawn away by the oxygen atoms and the remaining bond with hydrogen. By understanding the concept of oxidation states, students can predict how iodine and other elements will behave in various compounds, leading to a deeper comprehension of chemical reactions.

Chemical nomenclature provides a standardized method for naming chemical substances. Naming chemicals appropriately is pivotal for effective communication among scientists. For example, the name hydriodic acid corresponds to HI, which tells us it comprises hydrogen and iodine. The prefix 'hydro-' indicates the presence of hydrogen, and the suffix '-ic acid' points to the fact that iodine has a higher oxidation state minus one in this specific compound (in binary acids).

In the case of I₂, it's simply called iodine because it's an element in its diatomic form. For ICl, we refer to it as iodine monochloride, which infers that it's a compound consisting of one iodine atom and one chlorine atom. Correspondingly, HIO₄, with a more complex structure, is named periodic acid, which signals a peroxide linkage (as suggested by the 'per-' prefix) and that iodine is central to this molecule with an oxygen-rich environment.

Proper chemical nomenclature not only helps with identifying substances but also gives insight into the potential reactions and interactions those substances may undergo. The naming conventions carry valuable information such as the type of elements present and their respective quantities within a compound.

Balancing oxidation-reduction (redox) reactions is an integral skill in chemistry that ensures the conservation of mass and charge. Here, the principle that the total increase and decrease in oxidation numbers must balance out during a reaction is key. Each atom's oxidation number indicates its electron 'ownership' in a compound, and during a redox reaction, this ownership changes.

A balanced redox reaction is one where the number of electrons lost by the oxidized species equals the number of electrons gained by the reduced species. Achieving this balance often involves using coefficients to multiply the compounds in the reaction. This process not only ensures that the number of atoms for each element is conserved but also that the total charge before and after the reaction remains the same.

For example, in the reduction of iodine to hydriodic acid (I₂ to HI), we balance the iodine atoms first and then adjust the coefficients to ensure that both the atoms and charge are balanced. While the art of balancing equations may seem daunting, becoming proficient at it enhances a student's ability to decipher and predict the outcomes of chemical reactions.