Question

Write the chemical formula for each of the following, and indicate the oxidation state of the halogen or noble-gas atom in each: (a) krypton tetrafluoride, (b) hexafluoroantimonate ion, \((\mathbf{c})\) sodium hypoiodite, \((\mathbf{d})\) perbromic acid, (e) aluminum perchlorate, (f) iron(II) iodite.

Short answer

(a) Krypton Tetrafluoride: KrF4, Krypton oxidation state: +4 (b) Hexafluoroantimonate Ion: SbF6^-, Antimony oxidation state: +5 (c) Sodium Hypoiodite: NaIO, Iodine oxidation state: +1 (d) Perbromic Acid: HBrO4, Bromine oxidation state: +7 (e) Aluminum Perchlorate: Al(ClO4)3, Chlorine oxidation state: +7 (f) Iron(II) Iodite: Fe(IO2)2, Iodine oxidation state: +3

Step-by-step solution

a) Krypton Tetrafluoride

Write down the symbols for Krypton (Kr) and Fluorine (F). Since it is "tetrafluoride," there will be four Fluorine atoms. The chemical formula for Krypton Tetrafluoride is KrF4. Krypton in KrF4 is in its highest possible oxidation state (+4) because it is bonded to four fluorine atoms with a -1 oxidation state each.

b) Hexafluoroantimonate Ion

Write down the symbol for antimony (Sb) and Fluorine (F). This ion has six Fluorine atoms, and since it is an anion, it will have a negative charge. The chemical formula for Hexafluoroantimonate Ion is SbF6^-. Here, antimony (Sb) has an oxidation state of +5 because it is bonded to six fluorine atoms, each having a -1 oxidation state.

c) Sodium Hypoiodite

Write down the symbols for Sodium (Na), Iodine (I), and Oxygen (O). Hypoiodite means the presence of the ion in the compound, so the chemical formula for Sodium Hypoiodite is NaIO. The oxidation state of iodine is +1 because it is bonded to an oxygen atom with an oxidation state of -2 and a sodium atom with an oxidation state of +1.

d) Perbromic Acid

Write down the symbols for Hydrogen (H), Bromine (Br) and Oxygen (O). The "per" in perbromic acid means it has the maximum possible amount of oxygen atoms, which is BrO4. So the compound is an acid, and we need the hydrogen, resulting in the chemical formula HBrO4. The oxidation state of bromine is +7 because it is bonded to four oxygen atoms with an oxidation state of -2 and one hydrogen atom with an oxidation state of +1.

e) Aluminum Perchlorate

Write down the symbols for Aluminum (Al), Chlorine (Cl), and Oxygen (O). The "per" in perchlorate indicates the maximum possible amount of oxygen atoms, meaning ClO4. The compound is a salt, and we need to balance the charge of the ions. Aluminum has an oxidation state of +3, while perchlorate anion (ClO4^-) has a charge of -1. So, the chemical formula for Aluminum Perchlorate is Al(ClO4)3. In this compound, chlorine has an oxidation state of +7.

f) Iron(II) Iodite

Write down the symbols for Iron (Fe) and Iodine (I). The compound consists of Iron(II), meaning it has an oxidation state of +2, and iodite is a polyatomic ion (IO2^-). Since the charge of iron is +2 and iodite anion has a charge of -1, we need two iodite ions to balance it. The chemical formula for Iron(II) Iodite is Fe(IO2)2. In this compound, iodine has an oxidation state of +3.

Key concepts

Oxidation States

Understanding oxidation states is crucial in chemical nomenclature because it helps us determine how atoms form compounds. The oxidation state, or oxidation number, indicates how many electrons an atom has gained, lost, or shared when bonding with another atom. It is particularly important in understanding inorganic compounds, where elements combine in a variety of ways.

For example, in the compound krypton tetrafluoride ( KrF_4 ), krypton has an oxidation state of +4. This is because each fluorine atom, having a -1 oxidation state, is bonded to krypton, requiring krypton to give up electrons to form stable bonds.

The oxidation state can be derived from the known oxidation states of common atoms, such as fluorine always being -1, and by applying principles such as the conservation of charge. For instance, in hexafluoroantimonate ( SbF_6^- ), antimony's oxidation state is +5 because the six fluorine atoms contribute a total of -6, and the ion’s overall charge is -1, balancing the equation.

Chemical Formulas

Chemical formulas are shorthand expressions that represent the types and numbers of atoms present in a compound. These formulas not only show different elements but also their quantities, which is crucial for understanding the compound's makeup and behavior.

For example, krypton tetrafluoride is written as KrF_4 , meaning one krypton atom is bonded to four fluorine atoms. The prefixes like 'tetra-' in chemical nomenclature indicate the number of atoms of a particular element in the compound.

Writing the correct chemical formula ensures that the compound is electrically neutral unless specified as an ion. For example, in sodium hypoiodite ( NaIO ), the compound is neutral as the sum of the oxidation states (Na +1, I +1, O -2) equals zero.

• The formula HBrO_4 for perbromic acid indicates one hydrogen atom associated with a bromate group BrO_4 that contains maximum oxygen atoms bonded to bromine.
• For inorganic ions like hexafluoroantimonate ( SbF_6^- ), the negative charge is indicated as it represents a polyatomic ion alongside its formula.

Inorganic Chemistry

Inorganic chemistry primarily deals with compounds not centered around carbon, contrasting with organic chemistry. It includes a diverse array of substances, from metals and minerals to salts and more complex molecules found in the earth's crust or manufactured in laboratories.

Compounds such as these often involve bonding of metals with non-metals, as seen in examples like aluminum perchlorate ( Al(ClO_4)_3 ). Here, aluminum, a metal with a +3 oxidation state, combines with perchlorate ions, each with a -1 charge.

Inorganic nomenclature often involves naming ionic compounds by indicating the metal first, followed by the non-metal with an appropriate suffix or prefix that describes its oxidation state or molecular arrangement. Examples include:

• Krypton tetrafluoride, a simple molecular compound, where a noble gas krypton, typically inert, forms a stable compound with fluorine.
• Perbromic acid and hexafluoroantimonate, which reflect how diverse the chemistry can be even with seemingly simple elemental compositions.

Thus, appreciating the fundamentals of inorganic chemistry opens up possibilities in selecting the right materials for scientific and industrial applications.