Question

Name each of the following compounds. a. \(\operatorname{Fe}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{3}\) b. BrF c. \(\mathrm{K}_{2} \mathrm{O}_{2}\) d. \(\operatorname{SiBr}_{4}\) e. \(\mathrm{Cu}\left(\mathrm{MnO}_{4}\right)_{2}\) f. \(\mathrm{CaCrO}_{4}\)

Short answer

a. Iron(III) acetate b. Bromine monofluoride c. Potassium peroxide d. Silicon tetrabromide e. Copper(II) permanganate f. Calcium chromate

Step-by-step solution

(Naming Compound a)

(To name this compound, first observe that it consists of \(\operatorname{Fe}\) (Iron) and \(\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)\) which is a polyatomic ion called acetate. Since it is a compound involving a metal, cation naming rules apply, and the respective charge of the Iron atom indicates it as \(\operatorname{Fe^{III}}\) (Iron(III)). Therefore, the compound is called Iron(III) acetate.)

(Naming Compound b)

(To name this compound, observe that it consists of Br (Bromine) and F (Fluorine). These are two nonmetals, and so covalent naming rules apply. In this case, use prefixes to indicate the number of each type of atom in the molecule. Since there is only one atom of each element, the compound is called Bromine monofluoride.)

(Naming Compound c)

(To name this compound, first observe that it consists of K (Potassium) and O (Oxygen). Identify K as a metal and O as a nonmetal. Since K is an alkali metal with a +1 charge and O has a -2 charge, K forms the peroxide ion (\(\mathrm{O}_{2}^{2-}\)). Therefore, the compound is called Potassium peroxide.)

(Naming Compound d)

(To name this compound, observe that it consists of Si (Silicon) and Br (Bromine). These are both nonmetals, and so covalent naming rules apply. Since there are four Br atoms, the compound is called Silicon tetrabromide.)

(Naming Compound e)

(To name this compound, first observe that it consists of \(\mathrm{Cu}\) (Copper) and \(\left(\mathrm{MnO}_{4}\right)\) which is a polyatomic ion called permanganate. Since it is a compound involving a metal, cation naming rules apply, and the respective charge of the Copper atom indicates it as \(\operatorname{Cu^{II}}\) (Copper(II)). Therefore, the compound is called Copper(II) permanganate.)

(Naming Compound f)

(To name this compound, first observe that it consists of Ca (Calcium) and CrO (Chromate). Ca is a metal and chromate is a polyatomic anion (\(\mathrm{CrO}_{4}^{2-}\)). Since it is a compound involving a metal, cation naming rules apply. Therefore, the compound is called Calcium chromate.)

Key concepts

Ionic Compounds

Ionic compounds are formed from atoms that exchange electrons to achieve stability. Usually, this occurs between a metal and a nonmetal. Metals, located on the left side of the periodic table, tend to lose electrons and form positive ions or cations. Nonmetals, found on the right side, tend to gain electrons and form negative ions or anions.

When naming ionic compounds, follow these steps:

• Name the cation (metal) first and the anion (nonmetal) second.
• For metals with a fixed oxidation state, just use the element name. For metals with variable oxidation states, like \( ext{Fe}\) and \( ext{Cu}\) in this exercise, indicate the charge with Roman numerals inside parentheses.
• For the anion, use the root name of the element and add the suffix '-ide' (e.g., chloride for Cl).

A typical example from the exercise is Potassium peroxide \( ext{K}_2 ext{O}_2\). Here, Potassium (K) is a metal, and Oxygen forms a peroxide anion. Hence, we name it by stating the metal followed by the anion name formed from the molecule.

Covalent Compounds

Covalent compounds form when two nonmetals bond by sharing electrons. This allows them to attain a full outer electron shell, leading to stability. In naming covalent compounds, prefixes are crucial because they indicate the number of each type of atom present in the molecule.

Here are the steps for naming covalent compounds:

• Identify that both elements are nonmetals.
• Use the appropriate prefixes to denote the number of each atom. Common prefixes include mono- (1), di- (2), tri- (3), tetra- (4), etc.
• Name the first element using the full element name.
• Name the second element as if it were an anion, ending in '-ide'.

For instance, Bromine monofluoride \( ext{BrF}\) consists of one bromine and one fluorine atom. Following the naming rules, we use the prefix 'mono-' for one fluorine atom, though it is often omitted for the first element.

Polyatomic Ions

Understanding polyatomic ions is essential since they are multi-atom entities carrying a charge. Unlike simple ions, these possess more intricate structures and are present in many chemical compounds. Recognizing common polyatomic ions is crucial for mastering chemical nomenclature.

Common examples include:

• Acetate, \(\text{C}_2\text{H}_3\text{O}_2^-\)
• Permanganate, \(\text{MnO}_4^-\)
• Chromate, \(\text{CrO}_4^{2-}\)

When naming compounds containing polyatomic ions, use the name of the polyatomic ion directly. When a metal with a variable charge forms part of the compound (e.g., Iron(III) acetate \(\text{Fe}(\text{C}_2\text{H}_3\text{O}_2)_3\)), ensure the charge of the metal is indicated in Roman numerals, reflecting the ionic balance with the polyatomic ion.