Problem 158 - Chemistry An Atoms First Approach

Question

For each of the following ions, indicate the total number of protons and electrons in the ion. For the positive ions in the list, predict the formula of the simplest compound formed between each positive ion and the oxide ion. Name the compounds. For the negative ions in the list, predict the formula of the simplest compound formed between each negative ion and the aluminum ion. Name the compounds. a. \(\mathrm{Fe}^{2+}\) b. \(\mathrm{Fe}^{3+}\) c. \(B a^{2+}\) d. \(C s^{+}\) e. \(S^{2-}\) f. \(P^{3-}\) g. \(\mathrm{Br}^{-}\) \(\mathbf{h} . \mathbf{N}^{3-}\)

Step-by-Step Solution

Answer

The total number of protons and electrons in the given ions are as follows: a. \(\mathrm{Fe}^{2+}\): 26 protons, 24 electrons; forms \(\mathrm{FeO}\) (Iron (II) oxide) with oxide ion b. \(\mathrm{Fe}^{3+}\): 26 protons, 23 electrons; forms \(\mathrm{Fe_2O_3}\) (Iron (III) oxide) with oxide ion c. \(B a^{2+}\): 56 protons, 54 electrons; forms \(\mathrm{BaO}\) (Barium oxide) with oxide ion d. \(C s^{+}\) : 55 protons, 54 electrons; forms \(\mathrm{Cs_2O}\) (Cesium oxide) with oxide ion e. \(S^{2-}\) : 16 protons, 18 electrons; forms \(\mathrm{Al_2S_3}\) (Aluminum sulfide) with aluminum ion f. \(P^{3-}\) : 15 protons, 18 electrons; forms \(\mathrm{AlP}\) (Aluminum phosphide) with aluminum ion g. \(B r^{-}\) : 35 protons, 36 electrons; forms \(\mathrm{AlBr_3}\) (Aluminum bromide) with aluminum ion h. \(\mathrm{N}^{3-}\) : 7 protons, 10 electrons; forms \(\mathrm{AlN}\) (Aluminum nitride) with aluminum ion

Step 1: Finding the number of protons and electrons in each ion.

To find the number of protons in an ion, look at the atomic number of the element in the Periodic Table. The atomic number is equal to the number of protons. To find the number of electrons in an ion, subtract the charge of the ion from the number of protons. a. \(\mathrm{Fe}^{2+}\) Iron (Fe) has an atomic number of 26, so it has 26 protons. Since it has a charge of +2, it has 24 electrons (26 - 2). b. \(\mathrm{Fe}^{3+}\) Iron (Fe) still has 26 protons. With a charge of +3, it has 23 electrons (26 - 3). c. \(B a^{2+}\) Barium (Ba) has an atomic number of 56, so it has 56 protons. With a charge of +2, it has 54 electrons (56 - 2). d. \(C s^{+}\) Cesium (Cs) has an atomic number of 55, so it has 55 protons. With a charge of +1, it has 54 electrons (55 - 1). e. \(S^{2-}\) Sulfur (S) has an atomic number of 16, so it has 16 protons. With a charge of -2, it has 18 electrons (16 + 2). f. \(P^{3-}\) Phosphorus (P) has an atomic number of 15, so it has 15 protons. With a charge of -3, it has 18 electrons (15 + 3). g. \(B r^{-}\) Bromine (Br) has an atomic number of 35, so it has 35 protons. With a charge of -1, it has 36 electrons (35 + 1). h. \(\mathrm{N}^{3-}\) Nitrogen (N) has an atomic number of 7, so it has 7 protons. With a charge of -3, it has 10 electrons (7 + 3).

Step 2: Predicting the formula of the simplest compound with oxide ion or aluminum ion and naming the compounds.

For positive ions (Fe²⁺, Fe³⁺, Ba²⁺, Cs⁺), we'll predict the simplest compound formed with oxide ion (O²⁻). For negative ions (S²⁻, P³⁻, Br⁻, N³⁻), we'll predict the simplest compound formed with aluminum ion (Al³⁺). Remember that the total charges between the ions must balance out to create a neutral compound. a. \(\mathrm{Fe}^{2+}\) Fe²⁺ with O²⁻: \(\mathrm{FeO}\) (Iron (II) oxide) b. \(\mathrm{Fe}^{3+}\) Fe³⁺ with O²⁻: \(\mathrm{Fe_2O_3}\) (Iron (III) oxide) c. \(B a^{2+}\) Ba²⁺ with O²⁻: \(\mathrm{BaO}\) (Barium oxide) d. \(C s^{+}\) Cs⁺ with O²⁻: \(\mathrm{Cs_2O}\) (Cesium oxide) e. \(S^{2-}\) S²⁻ with Al³⁺: \(\mathrm{Al_2S_3}\) (Aluminum sulfide) f. \(P^{3-}\) P³⁻ with Al³⁺: \(\mathrm{AlP}\) (Aluminum phosphide) g. \(B r^{-}\) Br⁻ with Al³⁺: \(\mathrm{AlBr_3}\) (Aluminum bromide) h. \(\mathrm{N}^{3-}\) N³⁻ with Al³⁺: \(\mathrm{AlN}\) (Aluminum nitride)

Key Concepts

protons and electrons

Let's dive into the core building blocks of atoms: protons and electrons. Protons are positively charged particles located in the nucleus of an atom. The number of protons in an atom determines its atomic number, which corresponds to the specific element on the periodic table. For example, carbon with 6 protons has an atomic number of 6.
Electrons, on the other hand, are negatively charged particles that orbit the nucleus in various energy levels. While the number of protons within an atom remains constant, the number of electrons can vary when the atom becomes an ion. An ion is simply an atom that has gained or lost electrons, resulting in a net charge.

• Positive ions (cations) have fewer electrons than protons.
• Negative ions (anions) have more electrons than protons.

Understanding the interplay between protons and electrons is essential for revealing why substances behave the way they do.

oxide ion

The oxide ion is a well-known anion in the world of chemistry. This ion is represented as \(O^{2-}\), indicating that an oxygen atom has gained two extra electrons. This gives the ion a negative charge of -2 due to the excess electrons.
Oxygen typically has 8 protons and, in its neutral state, would have 8 electrons. However, when it forms an oxide ion, the total number of electrons becomes 10. Adding these extra electrons enhances the negative charge, making it more likely to bond with positively charged ions.
The oxide ion plays a critical role in forming compounds with metals, such as metal oxides. Examples include:

• Magnesium oxide (MgO), a compound between magnesium ions and oxide ions.
• Zinc oxide (ZnO), commonly used in sunscreen and cosmetics.

Overall, understanding the oxide ion is crucial for predicting the formation and properties of metal oxide compounds.

aluminum ion

The aluminum ion, denoted as \(Al^{3+}\), is an essential cation in several chemical reactions. In this form, aluminum has lost three electrons, leading to a positive charge of +3. Its regular atomic number is 13, meaning there are 13 protons in its nucleus.
Due to the loss of three electrons, the aluminum ion can effectively pair with negative ions to form neutral compounds. A familiar example is aluminum oxide (\(Al_2O_3\)), where aluminum ions bond with oxide ions.

• In reactions, the aluminum ion often partners with a similarly charged anion, such as a phosphate ion, to form compounds like aluminum phosphate (\(AlPO_4\)).

The ability of the aluminum ion to combine with diverse anions makes it versatile in various applications, from construction materials to electronic components.

neutral compounds

Neutral compounds arise when ions of opposing charges combine in a ratio that balances out their charges. These compounds carry no overall electrical charge. To achieve neutrality, the total positive charge must equal the total negative charge. This concept underpins the formation of many ionic compounds.
For instance, when sodium ions (Na\(^+\)) and chloride ions (Cl\(^-\)) combine, they form the neutral compound sodium chloride (NaCl). The single positive charge from the sodium ion is balanced by the single negative charge of the chloride ion.

• In cases with different charge magnitudes, such as magnesium fluoride (\(MgF_2\)), a 2:1 ratio balances the charges: two fluoride ions each with a -1 charge balance one magnesium ion with a +2 charge.

Grasping the concept of neutral compounds allows for the prediction and explanation of many key ionic interactions in chemistry.