Question

Write the formula for each of the following: a. nickel(III) oxide b. barium fluoride c. tin(IV) chloride d. silver sulfide e. copper(II) iodide f. lithium nitride

Short answer

a. Ni2O3, b. BaF2, c. SnCl4, d. Ag2S, e. CuI2, f. Li3N

Step-by-step solution

- Determine the Chemical Symbols

Identify the chemical symbols for all elements involved in each compound. For example, nickel is Ni, barium is Ba, tin is Sn, silver is Ag, copper is Cu, lithium is Li, oxygen is O, fluorine is F, chlorine is Cl, sulfur is S, iodine is I, and nitrogen is N.

- Recognize the Oxidation States

Understand the oxidation states given in Roman numerals. Nickel(III) has an oxidation state of +3, barium has an oxidation state of +2, tin(IV) has an oxidation state of +4, silver has a typical oxidation state of +1, copper(II) has an oxidation state of +2, and lithium has an oxidation state of +1. Oxygen is usually -2, fluorine is -1, chlorine is -1, sulfur is -2, iodine is -1, and nitrogen is -3.

- Write the Formulas

Combine the elements using their symbols and balance their charges to create neutral compounds: a. Nickel(III) oxide: Ni has +3 and O has -2, so the formula is Ni2O3. b. Barium fluoride: Ba has +2 and F has -1, so the formula is BaF2. c. Tin(IV) chloride: Sn has +4 and Cl has -1, so the formula is SnCl4. d. Silver sulfide: Ag has +1 and S has -2, so the formula is Ag2S. e. Copper(II) iodide: Cu has +2 and I has -1, so the formula is CuI2. f. Lithium nitride: Li has +1 and N has -3, so the formula is Li3N.

Key concepts

Chemical Symbols

To write chemical formulas, you first need to know the chemical symbols of the involved elements. These symbols are usually one or two letters, where the first letter is always capitalized, and if there's a second letter, it is lowercase. For instance, the chemical symbol for nickel is Ni, while for oxygen, it is O. Understanding these symbols is vital because they form the basis for writing and reading chemical formulas.
Here are some common chemical symbols you might find useful:

• Ni - Nickel
• Ba - Barium
• Sn - Tin
• Ag - Silver
• Cu - Copper
• Li - Lithium
• O - Oxygen
• F - Fluorine
• Cl - Chlorine
• S - Sulfur
• I - Iodine
• N - Nitrogen

Getting familiar with these symbols will make it easier for you to decode and form chemical compounds in your exercises.

Oxidation States

Oxidation states (or oxidation numbers) indicate the degree of oxidation of an atom within a compound. They are represented by Roman numerals. For instance, Nickel(III) means nickel has an oxidation state of +3. Recognizing these states helps to balance the electrons between different elements in a compound.
In practice, each element will have a preferred oxidation state or states:

• Nickel (Ni) can have +2 or +3.
• Barium (Ba) typically has +2.
• Tin (Sn) can be +2 or +4.
• Silver (Ag) is usually +1.
• Copper (Cu) can be +1 or +2.
• Lithium (Li) has +1.
• Oxygen (O) typically has -2.
• Fluorine (F), Chlorine (Cl), and Iodine (I) are typically -1.
• Sulfur (S) usually has -2.
• Nitrogen (N) is typically -3.

Understanding the oxidation states is crucial for correctly balancing the chemical formulas.

Neutral Compounds

Most compounds are neutral, meaning the total positive charge of the cations (positively charged ions) equals the total negative charge of the anions (negatively charged ions). To write a neutral compound's formula, balance the charges of each element.
For example, in Nickel(III) oxide, Ni has a +3 charge and O has a -2 charge. To balance these charges and form a neutral compound, you need two Ni atoms (total +6 charge) and three O atoms (total -6 charge), resulting in the formula Ni2O3.
Here are more examples from the given exercise:

• Barium (Ba, +2) and fluoride (F, -1): BaF2.
• Tin (Sn, +4) and chloride (Cl, -1): SnCl4.
• Silver (Ag, +1) and sulfide (S, -2): Ag2S.
• Copper (Cu, +2) and iodide (I, -1): CuI2.
• Lithium (Li, +1) and nitride (N, -3): Li3N.

Balancing the charges ensures the compound is neutral, which is a fundamental principle in chemistry.